X-Git-Url: http://www.privoxy.org/gitweb/?p=privoxy.git;a=blobdiff_plain;f=doc%2Fwebserver%2Fdeveloper-manual%2Fcoding.html;h=42fa1ca39726df8866fa847b1d64612715c51b24;hp=5b3c488356bce469d6affaa81636440ae17f75b3;hb=d5bba1fd0bce2185b191b7a8280cae9a62c829d6;hpb=16e9ef297b4cf15a61876abcc794e5a058500e4b diff --git a/doc/webserver/developer-manual/coding.html b/doc/webserver/developer-manual/coding.html index 5b3c4883..42fa1ca3 100644 --- a/doc/webserver/developer-manual/coding.html +++ b/doc/webserver/developer-manual/coding.html @@ -1,278 +1,135 @@ -Coding Guidelines
Privoxy Developer Manual
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5. Coding Guidelines

5.1. Introduction

This set of standards is designed to make our lives easier. It is - developed with the simple goal of helping us keep the "new and improved - Privoxy" consistent and reliable. Thus making - maintenance easier and increasing chances of success of the - project.

And that of course comes back to us as individuals. If we can - increase our development and product efficiencies then we can solve more - of the request for changes/improvements and in general feel good about - ourselves. ;->

5.2. Using Comments

5.2.1. Comment, Comment, Comment

Explanation:

Comment as much as possible without commenting the obvious. - For example do not comment "aVariable is equal to bVariable". - Instead explain why aVariable should be equal to the bVariable. - Just because a person can read code does not mean they will - understand why or what is being done. A reader may spend a lot - more time figuring out what is going on when a simple comment - or explanation would have prevented the extra research. Please - help your brother IJB'ers out!

The comments will also help justify the intent of the code. - If the comment describes something different than what the code - is doing then maybe a programming error is occurring.

Example:

+ +
/* if page size greater than 1k ... */
-if ( PageLength() > 1024 )
+
+
+
+  Coding Guidelines
+  
+  
+  
+  
+  
+  
+
+
+  
+  
+

4. Coding Guidelines

+
+

4.1. Introduction

+

This set of standards is designed to make our lives easier. It is developed with the simple goal of helping us + keep the "new and improved Privoxy" consistent and reliable. Thus making + maintenance easier and increasing chances of success of the project.

+

And that of course comes back to us as individuals. If we can increase our development and product + efficiencies then we can solve more of the request for changes/improvements and in general feel good about + ourselves. ;->

+
+
+

4.2. Using Comments

+
+

4.2.1. Comment, Comment, Comment

+

Explanation:

+

Comment as much as possible without commenting the obvious. For example do not comment "variable_a is equal + to variable_b". Instead explain why variable_a should be equal to the variable_b. Just because a person can + read code does not mean they will understand why or what is being done. A reader may spend a lot more time + figuring out what is going on when a simple comment or explanation would have prevented the extra research. + Please help your fellow Privoxy developers out!

+

The comments will also help justify the intent of the code. If the comment describes something different + than what the code is doing then maybe a programming error is occurring.

+

Example:

+ + +
+
/* if page size greater than 1k ... */
+if (page_length() > 1024)
 {
     ... "block" the page up ...
 }
 
 /* if page size is small, send it in blocks */
-if ( PageLength() > 1024 )
+if (page_length() > 1024)
 {
     ... "block" the page up ...
 }
 
 This demonstrates 2 cases of "what not to do".  The first is a
 "syntax comment".  The second is a comment that does not fit what
-is actually being done.

5.2.2. Use blocks for comments

Explanation:

Comments can help or they can clutter. They help when they - are differentiated from the code they describe. One line - comments do not offer effective separation between the comment - and the code. Block identifiers do, by surrounding the code - with a clear, definable pattern.

Example:

+ +
/*********************************************************************
+is actually being done.
+
+
+
+

4.2.2. Use blocks for comments

+

Explanation:

+

Comments can help or they can clutter. They help when they are differentiated from the code they describe. + One line comments do not offer effective separation between the comment and the code. Block identifiers do, by + surrounding the code with a clear, definable pattern.

+

Example:

+ + +
+
/*********************************************************************
  * This will stand out clearly in your code!
  *********************************************************************/
-if ( thisVariable == thatVariable )
+if (this_variable == that_variable)
 {
-   DoSomethingVeryImportant();
+   do_something_very_important();
 }
 
 
 /* unfortunately, this may not */
-if ( thisVariable == thatVariable )
+if (this_variable == that_variable)
 {
-   DoSomethingVeryImportant();
+   do_something_very_important();
 }
 
 
-if ( thisVariable == thatVariable ) /* this may not either */
+if (this_variable == that_variable) /* this may not either */
 {
-   DoSomethingVeryImportant();
-}

Exception:

If you are trying to add a small logic comment and do not - wish to "disrubt" the flow of the code, feel free to use a 1 - line comment which is NOT on the same line as the code.

5.2.3. Keep Comments on their own line

Explanation:

It goes back to the question of readability. If the comment - is on the same line as the code it will be harder to read than - the comment that is on its own line.

There are three exceptions to this rule, which should be - violated freely and often: during the definition of variables, - at the end of closing braces, when used to comment - parameters.

Example:

+ +
/*********************************************************************
+   do_something_very_important();
+}
+
+

Exception:

+

If you are trying to add a small logic comment and do not wish to "disrupt" the flow of the code, feel free + to use a 1 line comment which is NOT on the same line as the code.

+
+
+

4.2.3. Keep Comments on their own line

+

Explanation:

+

It goes back to the question of readability. If the comment is on the same line as the code it will be + harder to read than the comment that is on its own line.

+

There are three exceptions to this rule, which should be violated freely and often: during the definition of + variables, at the end of closing braces, when used to comment parameters.

+

Example:

+ + +
+
/*********************************************************************
  * This will stand out clearly in your code,
  * But the second example won't.
  *********************************************************************/
-if ( thisVariable == thatVariable )
+if (this_variable == this_variable)
 {
-   DoSomethingVeryImportant();
+   do_something_very_important();
 }
 
-if ( thisVariable == thatVariable ) /*can you see me?*/
+if (this_variable == this_variable) /*can you see me?*/
 {
-   DoSomethingVeryImportant(); /*not easily*/
+   do_something_very_important(); /*not easily*/
 }
 
 
@@ -282,822 +139,368 @@ if ( thisVariable == thatVariable ) /*can you see me?*/
 int urls_read     = 0;     /* # of urls read + rejected */
 int urls_rejected = 0;     /* # of urls rejected */
 
-if ( 1 == X )
+if (1 == X)
 {
-   DoSomethingVeryImportant();
+   do_something_very_important();
 }
 
 
-short DoSomethingVeryImportant(
+short do_something_very_important(
    short firstparam,   /* represents something */
    short nextparam     /* represents something else */ )
 {
    ...code here...
 
-}   /* -END- DoSomethingVeryImportant */

5.2.4. Comment each logical step

Explanation:

Logical steps should be commented to help others follow the - intent of the written code and comments will make the code more - readable.

If you have 25 lines of code without a comment, you should - probably go back into it to see where you forgot to put - one.

Most "for", "while", "do", etc... loops _probably_ need a - comment. After all, these are usually major logic - containers.

5.2.5. Comment All Functions Thoroughly

Explanation:

A reader of the code should be able to look at the comments - just prior to the beginning of a function and discern the - reason for its existence and the consequences of using it. The - reader should not have to read through the code to determine if - a given function is safe for a desired use. The proper - information thoroughly presented at the introduction of a - function not only saves time for subsequent maintenance or - debugging, it more importantly aids in code reuse by allowing a - user to determine the safety and applicability of any function - for the problem at hand. As a result of such benefits, all - functions should contain the information presented in the - addendum section of this document.

5.2.6. Comment at the end of braces if the - content is more than one screen length

Explanation:

Each closing brace should be followed on the same line by a - comment that describes the origination of the brace if the - original brace is off of the screen, or otherwise far away from - the closing brace. This will simplify the debugging, - maintenance, and readability of the code.

As a suggestion , use the following flags to make the - comment and its brace more readable:

use following a closing brace: } /* -END- if() or while () - or etc... */

Example:

+ +
if ( 1 == X )
+}   /* -END- do_something_very_important */
+
+
+
+

4.2.4. Comment each logical step

+

Explanation:

+

Logical steps should be commented to help others follow the intent of the written code and comments will + make the code more readable.

+

If you have 25 lines of code without a comment, you should probably go back into it to see where you forgot + to put one.

+

Most "for", "while", "do", etc... loops _probably_ need a comment. After all, these are usually major logic + containers.

+
+
+

4.2.5. Comment All Functions Thoroughly

+

Explanation:

+

A reader of the code should be able to look at the comments just prior to the beginning of a function and + discern the reason for its existence and the consequences of using it. The reader should not have to read + through the code to determine if a given function is safe for a desired use. The proper information thoroughly + presented at the introduction of a function not only saves time for subsequent maintenance or debugging, it + more importantly aids in code reuse by allowing a user to determine the safety and applicability of any + function for the problem at hand. As a result of such benefits, all functions should contain the information + presented in the addendum section of this document.

+
+
+

4.2.6. Comment at the end of braces if the content is more than one + screen length

+

Explanation:

+

Each closing brace should be followed on the same line by a comment that describes the origination of the + brace if the original brace is off of the screen, or otherwise far away from the closing brace. This will + simplify the debugging, maintenance, and readability of the code.

+

As a suggestion , use the following flags to make the comment and its brace more readable:

+

use following a closing brace: } /* -END- if() or while () or etc... */

+

Example:

+ + +
+
if (1 == X)
 {
-   DoSomethingVeryImportant();
+   do_something_very_important();
    ...some long list of commands...
 } /* -END- if x is 1 */
 
 or:
 
-if ( 1 == X )
+if (1 == X)
 {
-   DoSomethingVeryImportant();
+   do_something_very_important();
    ...some long list of commands...
-} /* -END- if ( 1 == X ) */

5.3. Naming Conventions

5.3.1. Variable Names

Explanation:

Use all lowercase, and seperate words via an underscore - ('_'). Do not start an identifier with an underscore. (ANSI C - reserves these for use by the compiler and system headers.) Do - not use identifiers which are reserved in ANSI C++. (E.g. - template, class, true, false, ...). This is in case we ever - decide to port Privoxy to C++.

Example:

int ms_iis5_hack = 0;

Instead of:

int msiis5hack = 0; int msIis5Hack = 0;

5.3.2. Function Names

Explanation:

Use all lowercase, and seperate words via an underscore - ('_'). Do not start an identifier with an underscore. (ANSI C - reserves these for use by the compiler and system headers.) Do - not use identifiers which are reserved in ANSI C++. (E.g. - template, class, true, false, ...). This is in case we ever - decide to port Privoxy to C++.

Example:

int load_some_file( struct client_state *csp )

Instead of:

int loadsomefile( struct client_state *csp )
-int loadSomeFile( struct client_state *csp )

5.3.3. Header file prototypes

Explanation:

Use a descriptive parameter name in the function prototype - in header files. Use the same parameter name in the header file - that you use in the c file.

Example:

(.h) extern int load_aclfile( struct client_state *csp );
-(.c) int load_aclfile( struct client_state *csp )

Instead of: -
(.h) extern int load_aclfile( struct client_state * ); or 
-(.h) extern int load_aclfile(); 
-(.c) int load_aclfile( struct client_state *csp )

5.3.4. Enumerations, and #defines

Explanation:

Use all capital letters, with underscores between words. Do - not start an identifier with an underscore. (ANSI C reserves - these for use by the compiler and system headers.)

Example:

(enumeration) : enum Boolean { FALSE, TRUE };
-(#define) : #define DEFAULT_SIZE 100;

Note: We have a standard naming scheme for #defines - that toggle a feature in the preprocessor: FEATURE_>, where - > is a short (preferably 1 or 2 word) description.

Example:

+ +
#define FEATURE_FORCE 1
+} /* -END- if (1 == X) */
+
+
+
+
+

4.3. Naming Conventions

+
+

4.3.1. Variable Names

+

Explanation:

+

Use all lowercase, and separate words via an underscore ('_'). Do not start an identifier with an + underscore. (ANSI C reserves these for use by the compiler and system headers.) Do not use identifiers which + are reserved in ANSI C++. (E.g. template, class, true, false, ...). This is in case we ever decide to port + Privoxy to C++.

+

Example:

+ + + + +
+
int ms_iis5_hack = 0;
+
+

Instead of:

+ + + + +
+
int msiis5hack = 0; int msIis5Hack = 0;
+
+
+
+

4.3.2. Function Names

+

Explanation:

+

Use all lowercase, and separate words via an underscore ('_'). Do not start an identifier with an + underscore. (ANSI C reserves these for use by the compiler and system headers.) Do not use identifiers which + are reserved in ANSI C++. (E.g. template, class, true, false, ...). This is in case we ever decide to port + Privoxy to C++.

+

Example:

+ + + + +
+
int load_some_file(struct client_state *csp)
+
+

Instead of:

+ + + + +
+
int loadsomefile(struct client_state *csp)
+int loadSomeFile(struct client_state *csp)
+
+
+
+

4.3.3. Header file prototypes

+

Explanation:

+

Use a descriptive parameter name in the function prototype in header files. Use the same parameter name in + the header file that you use in the c file.

+

Example:

+ + + + +
+
(.h) extern int load_aclfile(struct client_state *csp);
+(.c) int load_aclfile(struct client_state *csp)
+
+

Instead of:

+ + + + +
+
(.h) extern int load_aclfile(struct client_state *); or
+(.h) extern int load_aclfile();
+(.c) int load_aclfile(struct client_state *csp)
+
+
+
+

4.3.4. Enumerations, and #defines

+

Explanation:

+

Use all capital letters, with underscores between words. Do not start an identifier with an underscore. + (ANSI C reserves these for use by the compiler and system headers.)

+

Example:

+ + + + +
+
(enumeration) : enum Boolean {FALSE, TRUE};
+(#define) : #define DEFAULT_SIZE 100;
+
+

Note: We have a standard naming scheme for #defines + that toggle a feature in the preprocessor: FEATURE_>, where > is a short (preferably 1 or 2 word) + description.

+

Example:

+ + +
+
#define FEATURE_FORCE 1
 
 #ifdef FEATURE_FORCE
 #define FORCE_PREFIX blah
-#endif /* def FEATURE_FORCE */

5.3.5. Constants

Explanation:

Spell common words out entirely (do not remove vowels).

Use only widely-known domain acronyms and abbreviations. - Capitalize all letters of an acronym.

Use underscore (_) to separate adjacent acronyms and - abbreviations. Never terminate a name with an underscore.

Example:

#define USE_IMAGE_LIST 1

Instead of:

+ +
#define USE_IMG_LST 1 or 
+#endif /* def FEATURE_FORCE */
+
+

+
+

4.3.5. Constants

+

Explanation:

+

Spell common words out entirely (do not remove vowels).

+

Use only widely-known domain acronyms and abbreviations. Capitalize all letters of an acronym.

+

Use underscore (_) to separate adjacent acronyms and abbreviations. Never terminate a name with an + underscore.

+

Example:

+ + + + +
+
#define USE_IMAGE_LIST 1
+
+

Instead of:

+ + +
+
#define USE_IMG_LST 1 or
 #define _USE_IMAGE_LIST 1 or
-#define USE_IMAGE_LIST_ 1 or 
+#define USE_IMAGE_LIST_ 1 or
 #define use_image_list 1 or
-#define UseImageList 1

5.4. Using Space

5.4.1. Put braces on a line by themselves.

Explanation:

The brace needs to be on a line all by itself, not at the - end of the statement. Curly braces should line up with the - construct that they're associated with. This practice makes it - easier to identify the opening and closing braces for a - block.

Example:

+ +
if ( this == that )
+#define UseImageList 1
+
+
+
+
+

4.4. Using Space

+
+

4.4.1. Put braces on a line by themselves.

+

Explanation:

+

The brace needs to be on a line all by itself, not at the end of the statement. Curly braces should line up + with the construct that they're associated with. This practice makes it easier to identify the opening and + closing braces for a block.

+

Example:

+ + +
+
if (this == that)
 {
    ...
-}

Instead of:

if ( this == that ) { ... }

or

if ( this == that ) { ... }

Note: In the special case that the if-statement is - inside a loop, and it is trivial, i.e. it tests for a - condidtion that is obvious from the purpose of the block, - one-liners as above may optically preserve the loop structure - and make it easier to read.

Status: developer-discrection.

Example exception:

+ +
while ( more lines are read )
+}
+
+

Instead of:

+

if (this == that) { ... }

+

or

+

if (this == that) { ... }

+

Note: In the special case that the if-statement is + inside a loop, and it is trivial, i.e. it tests for a condition that is obvious from the purpose of the block, + one-liners as above may optically preserve the loop structure and make it easier to read.

+

Status: developer-discretion.

+

Example exception:

+ + +
+
while (more lines are read)
 {
    /* Please document what is/is not a comment line here */
-   if ( it's a comment ) continue;
+   if (it's a comment) continue;
 
-   do_something( line );
-}

5.4.2. ALL control statements should have a - block

Explanation:

Using braces to make a block will make your code more - readable and less prone to error. All control statements should - have a block defined.

Example:

+ +
if ( this == that )
+   do_something(line);
+}
+
+
+
+

4.4.2. ALL control statements should have a block

+

Explanation:

+

Using braces to make a block will make your code more readable and less prone to error. All control + statements should have a block defined.

+

Example:

+ + +
+
if (this == that)
 {
-   DoSomething();
-   DoSomethingElse();
-}

Instead of:

if ( this == that ) DoSomething(); DoSomethingElse();

or

if ( this == that ) DoSomething();

Note: The first example in "Instead of" will execute - in a manner other than that which the developer desired (per - indentation). Using code braces would have prevented this - "feature". The "explanation" and "exception" from the point - above also applies.

5.4.3. Do not belabor/blow-up boolean - expressions

Example:

structure->flag = ( condition );

Instead of:

if ( condition ) { structure->flag = 1; } else { - structure->flag = 0; }

Note: The former is readable and consice. The later - is wordy and inefficient. Please assume that any developer new - to the project has at least a "good" knowledge of C/C++. (Hope - I do not offend by that last comment ... 8-)

5.4.4. Use white space freely because it is - free

Explanation:

Make it readable. The notable exception to using white space - freely is listed in the next guideline.

Example:

int firstValue   = 0;
-int someValue    = 0;
-int anotherValue = 0;
-int thisVariable = 0;
-
-if ( thisVariable == thatVariable )
-
-firstValue = oldValue + ( ( someValue - anotherValue ) - whatever )

5.4.5. Don't use white space around structure - operators

Explanation:

- structure pointer operator ( "->" ) - member operator ( - "." ) - functions and parentheses

It is a general coding practice to put pointers, references, - and function parentheses next to names. With spaces, the - connection between the object and variable/function name is not - as clear.

Example:

aStruct->aMember;
-aStruct.aMember;
-FunctionName();

Instead of: aStruct -> aMember; aStruct . aMember; - FunctionName ();

5.4.6. Make the last brace of a function stand - out

Example:

+ +
int function1( ... )
+   do_something();
+   do_something_else();
+}
+
+

Instead of:

+

if (this == that) do_something(); do_something_else();

+

or

+

if (this == that) do_something();

+

Note: The first example in "Instead of" will execute + in a manner other than that which the developer desired (per indentation). Using code braces would have + prevented this "feature". The "explanation" and "exception" from the point above also applies.

+
+
+

4.4.3. Do not belabor/blow-up boolean expressions

+

Example:

+ + + + +
+
structure->flag = (condition);
+
+

Instead of:

+

if (condition) { structure->flag = 1; } else { structure->flag = 0; }

+

Note: The former is readable and concise. The later is + wordy and inefficient. Please assume that any developer new to the project has at least a "good" knowledge of + C/C++. (Hope I do not offend by that last comment ... 8-)

+
+
+

4.4.4. Use white space freely because it is free

+

Explanation:

+

Make it readable. The notable exception to using white space freely is listed in the next guideline.

+

Example:

+ + + + +
+
int first_value   = 0;
+int some_value    = 0;
+int another_value = 0;
+int this_variable = 0;
+
+
+
+

4.4.5. Don't use white space around structure operators

+

Explanation:

+

- structure pointer operator ( "->" ) - member operator ( "." ) - functions and parentheses

+

It is a general coding practice to put pointers, references, and function parentheses next to names. With + spaces, the connection between the object and variable/function name is not as clear.

+

Example:

+ + + + +
+
a_struct->a_member;
+a_struct.a_member;
+function_name();
+
+

Instead of: a_struct -> a_member; a_struct . + a_member; function_name ();

+
+
+

4.4.6. Make the last brace of a function stand out

+

Example:

+ + +
+
int function1( ... )
 {
    ...code...
-   return( retCode );
+   return(ret_code);
 
-}   /* -END- function1 */
+} /* -END- function1 */
 
 
 int function2( ... )
 {
-}   /* -END- function2 */

Instead of:

int function1( ... ) { ...code... return( retCode ); } int - function2( ... ) { }

Note: Use 1 blank line before the closing brace and 2 - lines afterwards. This makes the end of function standout to - the most casual viewer. Although function comments help - seperate functions, this is still a good coding practice. In - fact, I follow these rules when using blocks in "for", "while", - "do" loops, and long if {} statements too. After all whitespace - is free!

Status: developer-discrection on the number of blank - lines. Enforced is the end of function comments.

5.4.7. Use 3 character indentions

Explanation:

If some use 8 character TABs and some use 3 character TABs, - the code can look *very* ragged. So use 3 character indentions - only. If you like to use TABs, pass your code through a filter - such as "expand -t3" before checking in your code.

Example:

+ +
static const char * const url_code_map[256] =
+} /* -END- function2 */
+
+

Instead of:

+

int function1( ... ) { ...code... return(ret_code); } int function2( ... ) { }

+

Note: Use 1 blank line before the closing brace and 2 + lines afterward. This makes the end of function standout to the most casual viewer. Although function comments + help separate functions, this is still a good coding practice. In fact, I follow these rules when using blocks + in "for", "while", "do" loops, and long if {} statements too. After all whitespace is free!

+

Status: developer-discretion on the number of blank + lines. Enforced is the end of function comments.

+
+
+

4.4.7. Use 3 character indentions

+

Explanation:

+

If some use 8 character TABs and some use 3 character TABs, the code can look *very* ragged. So use 3 + character indentions only. If you like to use TABs, pass your code through a filter such as "expand -t3" before + checking in your code.

+

Example:

+ + +
+
static const char * const url_code_map[256] =
 {
    NULL, ...
 };
@@ -1105,422 +508,185 @@ CLASS="PROGRAMLISTING"
 
 int function1( ... )
 {
-   if ( 1 )
+   if (1)
    {
-      return( ALWAYS_TRUE );
+      return ALWAYS_TRUE;
    }
    else
    {
-      return( HOW_DID_YOU_GET_HERE );
+      return HOW_DID_YOU_GET_HERE;
    }
 
-   return( NEVER_GETS_HERE );
+   return NEVER_GETS_HERE;
 
-}

5.5. Initializing

5.5.1. Initialize all variables

Explanation:

Do not assume that the variables declared will not be used - until after they have been assigned a value somewhere else in - the code. Remove the chance of accidentally using an unassigned - variable.

Example:

short anShort = 0;
-float aFloat  = 0;
-struct *ptr = NULL;

Note: It is much easier to debug a SIGSEGV if the - message says you are trying to access memory address 00000000 - and not 129FA012; or arrayPtr[20] causes a SIGSEV vs. - arrayPtr[0].

Status: developer-discrection if and only if the - variable is assigned a value "shortly after" declaration.

5.6. Functions

5.6.1. Name functions that return a boolean as a - question.

Explanation:

Value should be phrased as a question that would logically - be answered as a true or false statement

Example:

ShouldWeBlockThis();
-ContainsAnImage();
-IsWebPageBlank();

5.6.2. Always specify a return type for a - function.

Explanation:

The default return for a function is an int. To avoid - ambiguity, create a return for a function when the return has a - purpose, and create a void return type if the function does not - need to return anything.

5.6.3. Minimize function calls when iterating by - using variables

Explanation:

It is easy to write the following code, and a clear argument - can be made that the code is easy to understand:

Example:

+ +
for ( size_t cnt = 0; cnt < blockListLength(); cnt ++ )
+}
+
+
+
+
+

4.5. Initializing

+
+

4.5.1. Initialize all variables

+

Explanation:

+

Do not assume that the variables declared will not be used until after they have been assigned a value + somewhere else in the code. Remove the chance of accidentally using an unassigned variable.

+

Example:

+ + + + +
+
short a_short = 0;
+float a_float  = 0;
+struct *ptr = NULL;
+
+

Note: It is much easier to debug a SIGSEGV if the + message says you are trying to access memory address 00000000 and not 129FA012; or array_ptr[20] causes a + SIGSEV vs. array_ptr[0].

+

Status: developer-discretion if and only if the + variable is assigned a value "shortly after" declaration.

+
+
+
+

4.6. Functions

+
+

4.6.1. Name functions that return a boolean as a question.

+

Explanation:

+

Value should be phrased as a question that would logically be answered as a true or false statement

+

Example:

+ + + + +
+
should_we_block_this();
+contains_an_image();
+is_web_page_blank();
+
+
+
+

4.6.2. Always specify a return type for a function.

+

Explanation:

+

The default return for a function is an int. To avoid ambiguity, create a return for a function when the + return has a purpose, and create a void return type if the function does not need to return anything.

+
+
+

4.6.3. Minimize function calls when iterating by using + variables

+

Explanation:

+

It is easy to write the following code, and a clear argument can be made that the code is easy to + understand:

+

Example:

+ + +
+
for (size_t cnt = 0; cnt < block_list_length(); cnt++)
 {
    ....
-}

Note: Unfortunately, this makes a function call for - each and every iteration. This increases the overhead in the - program, because the compiler has to look up the function each - time, call it, and return a value. Depending on what occurs in - the blockListLength() call, it might even be creating and - destroying structures with each iteration, even though in each - case it is comparing "cnt" to the same value, over and over. - Remember too - even a call to blockListLength() is a function - call, with the same overhead.

Instead of using a function call during the iterations, - assign the value to a variable, and evaluate using the - variable.

Example:

+ +
size_t len = blockListLength();
+}
+
+

Note: Unfortunately, this makes a function call for + each and every iteration. This increases the overhead in the program, because the compiler has to look up the + function each time, call it, and return a value. Depending on what occurs in the block_list_length() call, it + might even be creating and destroying structures with each iteration, even though in each case it is comparing + "cnt" to the same value, over and over. Remember too - even a call to block_list_length() is a function call, + with the same overhead.

+

Instead of using a function call during the iterations, assign the value to a variable, and evaluate using + the variable.

+

Example:

+ + +
+
size_t len = block_list_length();
 
-for ( size_t cnt = 0; cnt < len; cnt ++ )
+for (size_t cnt = 0; cnt < len; cnt++)
 {
    ....
-}

Exceptions: if the value of blockListLength() *may* - change or could *potentially* change, then you must code the - function call in the for/while loop.

5.6.4. Pass and Return by Const Reference

Explanation:

This allows a developer to define a const pointer and call - your function. If your function does not have the const - keyword, we may not be able to use your function. Consider - strcmp, if it were defined as: extern int strcmp( char *s1, - char *s2 );

I could then not use it to compare argv's in main: int main( - int argc, const char *argv[] ) { strcmp( argv[0], "privoxy" - ); }

Both these pointers are *const*! If the c runtime library - maintainers do it, we should too.

5.6.5. Pass and Return by Value

Explanation:

Most structures cannot fit onto a normal stack entry (i.e. - they are not 4 bytes or less). Aka, a function declaration - like: int load_aclfile( struct client_state csp )

would not work. So, to be consistent, we should declare all - prototypes with "pass by value": int load_aclfile( struct - client_state *csp )

5.6.6. Names of include files

Explanation:

Your include statements should contain the file name without - a path. The path should be listed in the Makefile, using -I as - processor directive to search the indicated paths. An exception - to this would be for some proprietary software that utilizes a - partial path to distinguish their header files from system or - other header files.

Example:

#include <iostream.h>     /* This is not a local include */
-#include "config.h"       /* This IS a local include */

Exception:

/* This is not a local include, but requires a path element. */ 
-#include <sys/fileName.h>

Note: Please! do not add "-I." to the Makefile - without a _very_ good reason. This duplicates the #include - "file.h" behaviour.

5.6.7. Provide multiple inclusion - protection

Explanation:

Prevents compiler and linker errors resulting from - redefinition of items.

Wrap each header file with the following syntax to prevent - multiple inclusions of the file. Of course, replace PROJECT_H - with your file name, with "." Changed to "_", and make it - uppercase.

Example:

+ +
#ifndef PROJECT_H_INCLUDED
+}
+
+

Exceptions: if the value of block_list_length() *may* + change or could *potentially* change, then you must code the function call in the for/while loop.

+
+
+

4.6.4. Pass and Return by Const Reference

+

Explanation:

+

This allows a developer to define a const pointer and call your function. If your function does not have the + const keyword, we may not be able to use your function. Consider strcmp, if it were defined as: extern int + strcmp(char *s1, char *s2);

+

I could then not use it to compare argv's in main: int main(int argc, const char *argv[]) { strcmp(argv[0], + "privoxy"); }

+

Both these pointers are *const*! If the c runtime library maintainers do it, we should too.

+
+
+

4.6.5. Pass and Return by Value

+

Explanation:

+

Most structures cannot fit onto a normal stack entry (i.e. they are not 4 bytes or less). Aka, a function + declaration like: int load_aclfile(struct client_state csp)

+

would not work. So, to be consistent, we should declare all prototypes with "pass by value": int + load_aclfile(struct client_state *csp)

+
+
+

4.6.6. Names of include files

+

Explanation:

+

Your include statements should contain the file name without a path. The path should be listed in the + Makefile, using -I as processor directive to search the indicated paths. An exception to this would be for some + proprietary software that utilizes a partial path to distinguish their header files from system or other header + files.

+

Example:

+ + + + +
+
#include <iostream.h>     /* This is not a local include */
+#include "config.h"       /* This IS a local include */
+
+

Exception:

+ + + + +
+
/* This is not a local include, but requires a path element. */
+#include <sys/fileName.h>
+
+

Note: Please! do not add "-I." to the Makefile without + a _very_ good reason. This duplicates the #include "file.h" behavior.

+
+
+

4.6.7. Provide multiple inclusion protection

+

Explanation:

+

Prevents compiler and linker errors resulting from redefinition of items.

+

Wrap each header file with the following syntax to prevent multiple inclusions of the file. Of course, + replace PROJECT_H with your file name, with "." Changed to "_", and make it uppercase.

+

Example:

+ + +
+
#ifndef PROJECT_H_INCLUDED
 #define PROJECT_H_INCLUDED
  ...
-#endif /* ndef PROJECT_H_INCLUDED */

5.6.8. Use `extern "C"` when appropriate

Explanation:

If our headers are included from C++, they must declare our - functions as `extern "C"`. This has no cost in C, but increases - the potential re-usability of our code.

Example:

+ +
#ifdef __cplusplus
+#endif /* ndef PROJECT_H_INCLUDED */
+
+
+
+

4.6.8. Use `extern "C"` when appropriate

+

Explanation:

+

If our headers are included from C++, they must declare our functions as `extern "C"`. This has no cost in + C, but increases the potential re-usability of our code.

+

Example:

+ + +
+
#ifdef __cplusplus
 extern "C"
 {
 #endif /* def __cplusplus */
@@ -1529,508 +695,204 @@ extern "C"
 
 #ifdef __cplusplus
 }
-#endif /* def __cplusplus */

5.6.9. Where Possible, Use Forward Struct - Declaration Instead of Includes

Explanation:

Useful in headers that include pointers to other struct's. - Modifications to excess header files may cause needless - compiles.

Example:

+ +
/*********************************************************************
+#endif /* def __cplusplus */
+
+
+
+

4.6.9. Where Possible, Use Forward Struct Declaration Instead of + Includes

+

Explanation:

+

Useful in headers that include pointers to other struct's. Modifications to excess header files may cause + needless compiles.

+

Example:

+ + +
+
/*********************************************************************
  * We're avoiding an include statement here!
  *********************************************************************/
 struct file_list;
-extern file_list *xyz;

Note: If you declare "file_list xyz;" (without the - pointer), then including the proper header file is necessary. - If you only want to prototype a pointer, however, the header - file is unneccessary.

Status: Use with discrection.

5.7. General Coding Practices

5.7.1. Turn on warnings

Explanation

Compiler warnings are meant to help you find bugs. You - should turn on as many as possible. With GCC, the switch is - "-Wall". Try and fix as many warnings as possible.

5.7.2. Provide a default case for all switch - statements

Explanation:

What you think is guaranteed is never really guaranteed. The - value that you don't think you need to check is the one that - someday will be passed. So, to protect yourself from the - unknown, always have a default step in a switch statement.

Example:

+ +
switch( hash_string( cmd ) )
+extern file_list *xyz;
+
+

Note: If you declare "file_list xyz;" (without the + pointer), then including the proper header file is necessary. If you only want to prototype a pointer, however, + the header file is unnecessary.

+

Status: Use with discretion.

+
+
+
+

4.7. General Coding Practices

+
+

4.7.1. Turn on warnings

+

Explanation

+

Compiler warnings are meant to help you find bugs. You should turn on as many as possible. With GCC, the + switch is "-Wall". Try and fix as many warnings as possible.

+
+
+

4.7.2. Provide a default case for all switch statements

+

Explanation:

+

What you think is guaranteed is never really guaranteed. The value that you don't think you need to check is + the one that someday will be passed. So, to protect yourself from the unknown, always have a default step in a + switch statement.

+

Example:

+ + +
+
switch (hash_string(cmd))
 {
-   case hash_actions_file :
+   case hash_actions_file:
       ... code ...
       break;
 
-   case hash_confdir :
+   case hash_confdir:
       ... code ...
       break;
 
-   default :
+   default:
       log_error( ... );
-      ... anomly code goes here ...
+      ... anomaly code goes here ...
       continue; / break; / exit( 1 ); / etc ...
 
-} /* end switch( hash_string( cmd ) ) */

Note: If you already have a default condition, you - are obviously exempt from this point. Of note, most of the - WIN32 code calls `DefWindowProc' after the switch statement. - This API call *should* be included in a default statement.

Another Note: This is not so much a readability issue - as a robust programming issue. The "anomly code goes here" may - be no more than a print to the STDERR stream (as in - load_config). Or it may really be an ABEND condition.

Status: Programmer discretion is advised.

5.7.3. Try to avoid falling through cases in a - switch statement.

Explanation:

In general, you will want to have a 'break' statement within - each 'case' of a switch statement. This allows for the code to - be more readable and understandable, and furthermore can - prevent unwanted surprises if someone else later gets creative - and moves the code around.

The language allows you to plan the fall through from one - case statement to another simply by omitting the break - statement within the case statement. This feature does have - benefits, but should only be used in rare cases. In general, - use a break statement for each case statement.

If you choose to allow fall through, you should comment both - the fact of the fall through and reason why you felt it was - necessary.

5.7.4. Use 'long' or 'short' Instead of - 'int'

Explanation:

On 32-bit platforms, int usually has the range of long. On - 16-bit platforms, int has the range of short.

Status: open-to-debate. In the case of most FSF - projects (including X/GNU-Emacs), there are typedefs to int4, - int8, int16, (or equivalence ... I forget the exact typedefs - now). Should we add these to IJB now that we have a "configure" - script?

5.7.5. Don't mix size_t and other types

Explanation:

The type of size_t varies across platforms. Do not make - assumptions about whether it is signed or unsigned, or about - how long it is. Do not compare a size_t against another - variable of a different type (or even against a constant) - without casting one of the values. Try to avoid using size_t if - you can.

5.7.6. Declare each variable and struct on its - own line.

Explanation:

It can be tempting to declare a series of variables all on - one line. Don't.

Example:

+ +
long a = 0;
+} /* end switch (hash_string(cmd)) */
+
+

Note: If you already have a default condition, you are + obviously exempt from this point. Of note, most of the WIN32 code calls `DefWindowProc' after the switch + statement. This API call *should* be included in a default statement.

+

Another Note: This is not so much a readability issue + as a robust programming issue. The "anomaly code goes here" may be no more than a print to the STDERR stream + (as in load_config). Or it may really be an abort condition.

+

Status: Programmer discretion is advised.

+
+
+

4.7.3. Try to avoid falling through cases in a switch + statement.

+

Explanation:

+

In general, you will want to have a 'break' statement within each 'case' of a switch statement. This allows + for the code to be more readable and understandable, and furthermore can prevent unwanted surprises if someone + else later gets creative and moves the code around.

+

The language allows you to plan the fall through from one case statement to another simply by omitting the + break statement within the case statement. This feature does have benefits, but should only be used in rare + cases. In general, use a break statement for each case statement.

+

If you choose to allow fall through, you should comment both the fact of the fall through and reason why you + felt it was necessary.

+
+
+

4.7.4. Don't mix size_t and other types

+

Explanation:

+

The type of size_t varies across platforms. Do not make assumptions about whether it is signed or unsigned, + or about how long it is. Do not compare a size_t against another variable of a different type (or even against + a constant) without casting one of the values.

+
+
+

4.7.5. Declare each variable and struct on its own line.

+

Explanation:

+

It can be tempting to declare a series of variables all on one line. Don't.

+

Example:

+ + +
+
long a = 0;
 long b = 0;
-long c = 0;

Instead of:

long a, b, c;

Explanation: - there is more room for comments on the - individual variables - easier to add new variables without - messing up the original ones - when searching on a variable to - find its type, there is less clutter to "visually" - eliminate

Exceptions: when you want to declare a bunch of loop - variables or other trivial variables; feel free to declare them - on 1 line. You should, although, provide a good comment on - their functions.

Status: developer-discrection.

5.7.7. Use malloc/zalloc sparingly

Explanation:

Create a local stuct (on the stack) if the variable will - live and die within the context of one function call.

Only "malloc" a struct (on the heap) if the variable's life - will extend beyond the context of one function call.

Example:

If a function creates a struct and stores a pointer to it in a
-list, then it should definately be allocated via `malloc'.

5.7.8. The Programmer Who Uses 'malloc' is - Responsible for Ensuring 'free'

Explanation:

If you have to "malloc" an instance, you are responsible for - insuring that the instance is `free'd, even if the deallocation - event falls within some other programmer's code. You are also - responsible for ensuring that deletion is timely (i.e. not too - soon, not too late). This is known as "low-coupling" and is a - "good thing (tm)". You may need to offer a - free/unload/destuctor type function to accomodate this.

Example:

int load_re_filterfile( struct client_state *csp ) { ... }
-static void unload_re_filterfile( void *f ) { ... }

Exceptions:

The developer cannot be expected to provide `free'ing - functions for C run-time library functions ... such as - `strdup'.

Status: developer-discrection. The "main" use of this - standard is for allocating and freeing data structures (complex - or nested).

5.7.9. Add loaders to the `file_list' structure - and in order

Explanation:

I have ordered all of the "blocker" file code to be in alpha - order. It is easier to add/read new blockers when you expect a - certain order.

Note: It may appear that the alpha order is broken in - places by POPUP tests coming before PCRS tests. But since - POPUPs can also be referred to as KILLPOPUPs, it is clear that - it should come first.

5.7.10. "Uncertain" new code and/or changes to - exitinst code, use FIXME

Explanation:

If you have enough confidence in new code or confidence in - your changes, but are not *quite* sure of the reprocussions, - add this:

/* FIXME: this code has a logic error on platform XYZ, * - attempthing to fix */ #ifdef PLATFORM ...changed code here... - #endif

or:

/* FIXME: I think the original author really meant this... - */ ...changed code here...

or:

/* FIXME: new code that *may* break something else... */ - ...new code here...

Note: If you make it clear that this may or may not - be a "good thing (tm)", it will be easier to identify and - include in the project (or conversly exclude from the - project).

5.8. Addendum: Template for files and function - comment blocks:

Example for file comments:

+ +
const char FILENAME_rcs[] = "$Id: developer-manual.sgml,v 1.25 2002/04/06 05:07:28 hal9 Exp $";
-/*********************************************************************
+long c = 0;
+
+

Instead of:

+

long a, b, c;

+

Explanation: - there is more room for comments on the + individual variables - easier to add new variables without messing up the original ones - when searching on a + variable to find its type, there is less clutter to "visually" eliminate

+

Exceptions: when you want to declare a bunch of loop + variables or other trivial variables; feel free to declare them on one line. You should, although, provide a + good comment on their functions.

+

Status: developer-discretion.

+
+
+

4.7.6. Use malloc/zalloc sparingly

+

Explanation:

+

Create a local struct (on the stack) if the variable will live and die within the context of one function + call.

+

Only "malloc" a struct (on the heap) if the variable's life will extend beyond the context of one function + call.

+

Example:

+ + + + +
+
If a function creates a struct and stores a pointer to it in a
+list, then it should definitely be allocated via `malloc'.
+
+
+
+

4.7.7. The Programmer Who Uses 'malloc' is Responsible for Ensuring + 'free'

+

Explanation:

+

If you have to "malloc" an instance, you are responsible for insuring that the instance is `free'd, even if + the deallocation event falls within some other programmer's code. You are also responsible for ensuring that + deletion is timely (i.e. not too soon, not too late). This is known as "low-coupling" and is a "good thing + (tm)". You may need to offer a free/unload/destructor type function to accommodate this.

+

Example:

+ + + + +
+
int load_re_filterfile(struct client_state *csp) { ... }
+static void unload_re_filterfile(void *f) { ... }
+
+

Exceptions:

+

The developer cannot be expected to provide `free'ing functions for C run-time library functions ... such as + `strdup'.

+

Status: developer-discretion. The "main" use of this + standard is for allocating and freeing data structures (complex or nested).

+
+
+

4.7.8. Add loaders to the `file_list' structure and in order

+

Explanation:

+

I have ordered all of the "blocker" file code to be in alpha order. It is easier to add/read new blockers + when you expect a certain order.

+

Note: It may appear that the alpha order is broken in + places by POPUP tests coming before PCRS tests. But since POPUPs can also be referred to as KILLPOPUPs, it is + clear that it should come first.

+
+
+

4.7.9. "Uncertain" new code and/or changes to existing code, use + XXX

+

Explanation:

+

If you have enough confidence in new code or confidence in your changes, but are not *quite* sure of the + repercussions, add this:

+

/* XXX: this code has a logic error on platform XYZ, * attempting to fix */ #ifdef PLATFORM ...changed code + here... #endif

+

or:

+

/* XXX: I think the original author really meant this... */ ...changed code here...

+

or:

+

/* XXX: new code that *may* break something else... */ ...new code here...

+

Note: If you make it clear that this may or may not be + a "good thing (tm)", it will be easier to identify and include in the project (or conversely exclude from the + project).

+
+
+
+

4.8. Addendum: Template for files and function comment blocks:

+

Example for file comments:

+ + +
+
/*********************************************************************
  *
- * File        :  $Source$
+ * File        :  $Source
  *
  * Purpose     :  (Fill me in with a good description!)
  *
- * Copyright   :  Written by and Copyright (C) 2001 the SourceForge
- *                Privoxy team. http://www.privoxy.org/
- *
- *                Based on the Internet Junkbuster originally written
- *                by and Copyright (C) 1997 Anonymous Coders and
- *                Junkbusters Corporation.  http://www.junkbusters.com
+ * Copyright   :  Written by and Copyright (C) 2001-2009
+ *                the Privoxy team. https://www.privoxy.org/
  *
  *                This program is free software; you can redistribute it
  *                and/or modify it under the terms of the GNU General
@@ -2046,12 +908,10 @@ CLASS="PROGRAMLISTING"
  *
  *                The GNU General Public License should be included with
  *                this file.  If not, you can view it at
- *                http://www.gnu.org/copyleft/gpl.html
- *                or write to the Free Software Foundation, Inc., 59
- *                Temple Place - Suite 330, Boston, MA  02111-1307, USA.
- *
- * Revisions   :
- *    $Log$
+ *                http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ *                or write to the Free Software Foundation, Inc.,
+ *                51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 ,
+ *                USA
  *
  *********************************************************************/
 
@@ -2060,55 +920,30 @@ CLASS="PROGRAMLISTING"
 
    ...necessary include files for us to do our work...
 
-const char FILENAME_h_rcs[] = FILENAME_H_VERSION;

Note: This declares the rcs variables that should be - added to the "show-proxy-args" page. If this is a brand new - creation by you, you are free to change the "Copyright" section - to represent the rights you wish to maintain.

Note: The formfeed character that is present right - after the comment flower box is handy for (X|GNU)Emacs users to - skip the verbige and get to the heart of the code (via - `forward-page' and `backward-page'). Please include it if you - can.

Example for file header comments:

+ +
#ifndef _FILENAME_H
+const char FILENAME_h_rcs[] = FILENAME_H_VERSION;
+
+

Note: This declares the rcs variables that should be + added to the "show-version" page. If this is a brand new creation by you, you are free to change the "Copyright" + section to represent the rights you wish to maintain.

+

Note: The formfeed character that is present right after + the comment flower box is handy for (X|GNU)Emacs users to skip the verbiage and get to the heart of the code (via + `forward-page' and `backward-page'). Please include it if you can.

+

Example for file header comments:

+ + +
+
#ifndef _FILENAME_H
 #define _FILENAME_H
-#define FILENAME_H_VERSION "$Id: developer-manual.sgml,v 1.25 2002/04/06 05:07:28 hal9 Exp $"
 /*********************************************************************
  *
- * File        :  $Source$
+ * File        :  $Source
  *
  * Purpose     :  (Fill me in with a good description!)
  *
- * Copyright   :  Written by and Copyright (C) 2001 the SourceForge
- *                Privoxy team. http://www.privoxy.org/
- *
- *                Based on the Internet Junkbuster originally written
- *                by and Copyright (C) 1997 Anonymous Coders and
- *                Junkbusters Corporation.  http://www.junkbusters.com
+ * Copyright   :  Written by and Copyright (C) 2001-2009
+ *                the Privoxy team. https://www.privoxy.org/
  *
  *                This program is free software; you can redistribute it
  *                and/or modify it under the terms of the GNU General
@@ -2124,12 +959,10 @@ CLASS="PROGRAMLISTING"
  *
  *                The GNU General Public License should be included with
  *                this file.  If not, you can view it at
- *                http://www.gnu.org/copyleft/gpl.html
- *                or write to the Free Software Foundation, Inc., 59
- *                Temple Place - Suite 330, Boston, MA  02111-1307, USA.
- *
- * Revisions   :
- *    $Log$
+ *                http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ *                or write to the Free Software Foundation, Inc.,
+ *                51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 ,
+ *                USA
  *
  *********************************************************************/
 
@@ -2158,24 +991,15 @@ extern const char FILENAME_h_rcs[];
   Local Variables:
   tab-width: 3
   end:
-*/

Example for function comments:

+ +
/*********************************************************************
+*/
+
+

Example for function comments:

+ + +
+
/*********************************************************************
  *
  * Function    :  FUNCTION_NAME
  *
@@ -2188,78 +1012,33 @@ CLASS="PROGRAMLISTING"
  * Returns     :  0 => Ok, everything else is an error.
  *
  *********************************************************************/
-int FUNCTION_NAME( void *param1, const char *x )
+int FUNCTION_NAME(void *param1, const char *x)
 {
    ...
-   return( 0 );
+   return 0;
 
-}

Note: If we all follow this practice, we should be - able to parse our code to create a "self-documenting" web - page.


PrevHomeNext
Documentation Guidelines Version Control Guidelines
\ No newline at end of file +}
+
+

Note: If we all follow this practice, we should be able + to parse our code to create a "self-documenting" web page.

+
+
+ + +