kmx git

Commit	Date	Message
607b668f	2022-02-10T11:33:49	MSVC: Eliminate C4996 warnings in API libs The primary purpose of this is to encourage adoption of libjpeg-turbo in downstream Windows projects that forbid the use of "deprecated" functions. libjpeg-turbo's usage of those functions was not actually unsafe, because: - libjpeg-turbo always checks the return value of fopen() and ensures that a NULL filename can never be passed to it. - libjpeg-turbo always checks the return value of getenv() and never passes a NULL argument to it. - The sprintf() calls in format_message() (jerror.c) could never overflow the destination string buffer or leave it unterminated as long as the buffer was at least JMSG_LENGTH_MAX bytes in length, as instructed. (Regardless, this commit replaces those calls with snprintf() calls.) - libjpeg-turbo never uses sscanf() to read strings or multi-byte character arrays. - Because of b7d6e84d6a9283dc2bc50ef9fcaadc0cdeb25c9f, wrjpgcom explicitly checks the bounds of the source and destination strings before calling strcat() and strcpy(). - libjpeg-turbo always ensures that the destination string is terminated when using strncpy(). (548490fe5e2aa31cb00f6602d5a478b068b99682 made this explicit.) Regarding thread safety: Technically speaking, getenv() is not thread-safe, because the returned pointer may be invalidated if another thread sets the same environment variable between the time that the first thread calls getenv() and the time that that thread uses the return value. In practice, however, this could only occur with libjpeg-turbo if: (1) A multithreaded calling application used the deprecated and undocumented TJFLAG_FORCEMMX/TJFLAG_FORCESSE/TJFLAG_FORCESSE2 flags in the TurboJPEG API or set one of the corresponding environment variables (which are only intended for testing purposes.) Since the TurboJPEG API library only ever passed string constants to putenv(), the only inherent risk (i.e. the only risk introduced by the library and not the calling application) was that the SIMD extensions may have read an incorrect value from one of the aforementioned environment variables. or (2) A multithreaded calling application modified the value of the JPEGMEM environment variable in one thread while another thread was reading the value of that environment variable (in the body of jpeg_create_compress() or jpeg_create_decompress().) Given that the libjpeg API provides a thread-safe way for applications to modify the default memory limit without using the JPEGMEM environment variable, direct modification of that environment variable by calling applications is not supported. Microsoft's implementation of getenv_s() does not claim to be thread-safe either, so this commit uses getenv_s() solely to mollify Visual Studio. New inline functions and macros (GETENV_S() and PUTENV_S) wrap getenv_s()/_putenv_s() when building for Visual Studio and getenv()/setenv() otherwise, but GETENV_S()/PUTENV_S() provide no advantages over getenv()/setenv() other than parameter validation. They are implemented solely for convenience. Technically speaking, strerror() is not thread-safe, because the returned pointer may be invalidated if another thread changes the locale and/or calls strerror() between the time that the first thread calls strerror() and the time that that thread uses the return value. In practice, however, this could only occur with libjpeg-turbo if a multithreaded calling application encountered a file I/O error in tjLoadImage() or tjSaveImage(). Since both of those functions immediately copy the string returned from strerror() into a thread-local buffer, the risk is minimal, and the worst case would involve an incorrect error string being reported to the calling application. Regardless, this commit uses strerror_s() in the TurboJPEG API library when building for Visual Studio. Note that strerror_r() could have been used on Un*x systems, but it would have been necessary to handle both the POSIX and GNU implementations of that function and perform widespread compatibility testing. Such is left as an exercise for another day. Fixes #568
3179f330	2021-01-04T14:54:35	tjexample.c: Fix mem leak if tjTransform() fails Fixes #479
00607ec2	2020-01-08T14:22:35	Eliminate unnecessary NULL checks before tjFree() + document that tjFree() accepts NULL pointers without complaint. Effectively, it has had that behavior all along, but the API does not guarantee that tjFree() will be implemented with free() behind the scenes, so it's best to formalize the behavior.
6399d0a6	2019-04-23T14:10:04	Fix code formatting/style issues ... ... including, but not limited to: - unused macros - private functions not marked as static - unprototyped global functions - variable shadowing (detected by various non-default GCC 8 warning options)
bce58f48	2019-04-12T07:49:35	Consistify formatting of macros in TurboJPEG code
293263c3	2018-03-17T15:14:35	Format preprocessor macros more consistently Within the libjpeg API code, it seems to be more the convention than not to separate the macro name and value by two or more spaces, which improves general readability. Making this consistent across all of libjpeg-turbo is less about my individual preferences and more about making it easy to automatically detect variations from our chosen formatting convention. I intend to release the script I'm using to validate this stuff, once it matures and stabilizes a bit.
19c791cd	2018-03-08T10:55:20	Improve code formatting consistency With rare exceptions ... - Always separate line continuation characters by one space from preceding code. - Always use two-space indentation. Never use tabs. - Always use K&R-style conditional blocks. - Always surround operators with spaces, except in raw assembly code. - Always put a space after, but not before, a comma. - Never put a space between type casts and variables/function calls. - Never put a space between the function name and the argument list in function declarations and prototypes. - Always surround braces ('{' and '}') with spaces. - Always surround statements (if, for, else, catch, while, do, switch) with spaces. - Always attach pointer symbols ('' and '') to the variable or function name. - Always precede pointer symbols ('' and '**') by a space in type casts. - Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG API libraries (using min() from tjutil.h is still necessary for TJBench.) - Where it makes sense (particularly in the TurboJPEG code), put a blank line after variable declaration blocks. - Always separate statements in one-liners by two spaces. The purpose of this was to ease maintenance on my part and also to make it easier for contributors to figure out how to format patch submissions. This was admittedly confusing (even to me sometimes) when we had 3 or 4 different style conventions in the same source tree. The new convention is more consistent with the formatting of other OSS code bases. This commit corrects deviations from the chosen formatting style in the libjpeg API code and reformats the TurboJPEG API code such that it conforms to the same standard. NOTES: - Although it is no longer necessary for the function name in function declarations to begin in Column 1 (this was historically necessary because of the ansi2knr utility, which allowed libjpeg to be built with non-ANSI compilers), we retain that formatting for the libjpeg code because it improves readability when using libjpeg's function attribute macros (GLOBAL(), etc.) - This reformatting project was accomplished with the help of AStyle and Uncrustify, although neither was completely up to the task, and thus a great deal of manual tweaking was required. Note to developers of code formatting utilities: the libjpeg-turbo code base is an excellent test bed, because AFAICT, it breaks every single one of the utilities that are currently available. - The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been formatted to match the SSE2 code (refer to ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to bother with this, but the Loongson MMI implementation demonstrated that there is still academic value to the MMX implementation, as an algorithmic model for other 64-bit vector implementations. Thus, it is desirable to improve its readability in the same manner as that of the SSE2 implementation.
8c40ac8a	2017-11-16T18:46:01	Add TurboJPEG C example and clean up Java example Also rename example.c --> example.txt and add a disclaimer to that file so people will stop trying to compile it.

607b668f

2022-02-10T11:33:49

MSVC: Eliminate C4996 warnings in API libs The primary purpose of this is to encourage adoption of libjpeg-turbo in downstream Windows projects that forbid the use of "deprecated" functions. libjpeg-turbo's usage of those functions was not actually unsafe, because: - libjpeg-turbo always checks the return value of fopen() and ensures that a NULL filename can never be passed to it. - libjpeg-turbo always checks the return value of getenv() and never passes a NULL argument to it. - The sprintf() calls in format_message() (jerror.c) could never overflow the destination string buffer or leave it unterminated as long as the buffer was at least JMSG_LENGTH_MAX bytes in length, as instructed. (Regardless, this commit replaces those calls with snprintf() calls.) - libjpeg-turbo never uses sscanf() to read strings or multi-byte character arrays. - Because of b7d6e84d6a9283dc2bc50ef9fcaadc0cdeb25c9f, wrjpgcom explicitly checks the bounds of the source and destination strings before calling strcat() and strcpy(). - libjpeg-turbo always ensures that the destination string is terminated when using strncpy(). (548490fe5e2aa31cb00f6602d5a478b068b99682 made this explicit.) Regarding thread safety: Technically speaking, getenv() is not thread-safe, because the returned pointer may be invalidated if another thread sets the same environment variable between the time that the first thread calls getenv() and the time that that thread uses the return value. In practice, however, this could only occur with libjpeg-turbo if: (1) A multithreaded calling application used the deprecated and undocumented TJFLAG_FORCEMMX/TJFLAG_FORCESSE/TJFLAG_FORCESSE2 flags in the TurboJPEG API or set one of the corresponding environment variables (which are only intended for testing purposes.) Since the TurboJPEG API library only ever passed string constants to putenv(), the only inherent risk (i.e. the only risk introduced by the library and not the calling application) was that the SIMD extensions may have read an incorrect value from one of the aforementioned environment variables. or (2) A multithreaded calling application modified the value of the JPEGMEM environment variable in one thread while another thread was reading the value of that environment variable (in the body of jpeg_create_compress() or jpeg_create_decompress().) Given that the libjpeg API provides a thread-safe way for applications to modify the default memory limit without using the JPEGMEM environment variable, direct modification of that environment variable by calling applications is not supported. Microsoft's implementation of getenv_s() does not claim to be thread-safe either, so this commit uses getenv_s() solely to mollify Visual Studio. New inline functions and macros (GETENV_S() and PUTENV_S) wrap getenv_s()/_putenv_s() when building for Visual Studio and getenv()/setenv() otherwise, but GETENV_S()/PUTENV_S() provide no advantages over getenv()/setenv() other than parameter validation. They are implemented solely for convenience. Technically speaking, strerror() is not thread-safe, because the returned pointer may be invalidated if another thread changes the locale and/or calls strerror() between the time that the first thread calls strerror() and the time that that thread uses the return value. In practice, however, this could only occur with libjpeg-turbo if a multithreaded calling application encountered a file I/O error in tjLoadImage() or tjSaveImage(). Since both of those functions immediately copy the string returned from strerror() into a thread-local buffer, the risk is minimal, and the worst case would involve an incorrect error string being reported to the calling application. Regardless, this commit uses strerror_s() in the TurboJPEG API library when building for Visual Studio. Note that strerror_r() could have been used on Un*x systems, but it would have been necessary to handle both the POSIX and GNU implementations of that function and perform widespread compatibility testing. Such is left as an exercise for another day. Fixes #568

3179f330

2021-01-04T14:54:35

tjexample.c: Fix mem leak if tjTransform() fails Fixes #479

00607ec2

2020-01-08T14:22:35

Eliminate unnecessary NULL checks before tjFree() + document that tjFree() accepts NULL pointers without complaint. Effectively, it has had that behavior all along, but the API does not guarantee that tjFree() will be implemented with free() behind the scenes, so it's best to formalize the behavior.

6399d0a6

2019-04-23T14:10:04

Fix code formatting/style issues ... ... including, but not limited to: - unused macros - private functions not marked as static - unprototyped global functions - variable shadowing (detected by various non-default GCC 8 warning options)

bce58f48

2019-04-12T07:49:35

Consistify formatting of macros in TurboJPEG code

293263c3

2018-03-17T15:14:35

Format preprocessor macros more consistently Within the libjpeg API code, it seems to be more the convention than not to separate the macro name and value by two or more spaces, which improves general readability. Making this consistent across all of libjpeg-turbo is less about my individual preferences and more about making it easy to automatically detect variations from our chosen formatting convention. I intend to release the script I'm using to validate this stuff, once it matures and stabilizes a bit.

19c791cd

2018-03-08T10:55:20

Improve code formatting consistency With rare exceptions ... - Always separate line continuation characters by one space from preceding code. - Always use two-space indentation. Never use tabs. - Always use K&R-style conditional blocks. - Always surround operators with spaces, except in raw assembly code. - Always put a space after, but not before, a comma. - Never put a space between type casts and variables/function calls. - Never put a space between the function name and the argument list in function declarations and prototypes. - Always surround braces ('{' and '}') with spaces. - Always surround statements (if, for, else, catch, while, do, switch) with spaces. - Always attach pointer symbols ('*' and '**') to the variable or function name. - Always precede pointer symbols ('*' and '**') by a space in type casts. - Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG API libraries (using min() from tjutil.h is still necessary for TJBench.) - Where it makes sense (particularly in the TurboJPEG code), put a blank line after variable declaration blocks. - Always separate statements in one-liners by two spaces. The purpose of this was to ease maintenance on my part and also to make it easier for contributors to figure out how to format patch submissions. This was admittedly confusing (even to me sometimes) when we had 3 or 4 different style conventions in the same source tree. The new convention is more consistent with the formatting of other OSS code bases. This commit corrects deviations from the chosen formatting style in the libjpeg API code and reformats the TurboJPEG API code such that it conforms to the same standard. NOTES: - Although it is no longer necessary for the function name in function declarations to begin in Column 1 (this was historically necessary because of the ansi2knr utility, which allowed libjpeg to be built with non-ANSI compilers), we retain that formatting for the libjpeg code because it improves readability when using libjpeg's function attribute macros (GLOBAL(), etc.) - This reformatting project was accomplished with the help of AStyle and Uncrustify, although neither was completely up to the task, and thus a great deal of manual tweaking was required. Note to developers of code formatting utilities: the libjpeg-turbo code base is an excellent test bed, because AFAICT, it breaks every single one of the utilities that are currently available. - The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been formatted to match the SSE2 code (refer to ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to bother with this, but the Loongson MMI implementation demonstrated that there is still academic value to the MMX implementation, as an algorithmic model for other 64-bit vector implementations. Thus, it is desirable to improve its readability in the same manner as that of the SSE2 implementation.

8c40ac8a

2017-11-16T18:46:01

Add TurboJPEG C example and clean up Java example Also rename example.c --> example.txt and add a disclaimer to that file so people will stop trying to compile it.

kc3-lang/libjpeg-turbo/tjexample.c

tjexample.c

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