path: root/include/string.h
AgeCommit message (Collapse)AuthorLines
2013-11-24restore type of NULL to void * except when used in C++ programsRich Felker-0/+4
unfortunately this eliminates the ability of the compiler to diagnose some dangerous/incorrect usage, but POSIX requires (as an extension to the C language, i.e. CX shaded) that NULL have type void *. plain C allows it to be defined as any null pointer constant. the definition 0L is preserved for C++ rather than reverting to plain 0 to avoid dangerous behavior in non-conforming programs which use NULL as a variadic sentinel. (it's impossible to use (void *)0 for C++ since C++ lacks the proper implicit pointer conversions, and other popular alternatives like the GCC __null extension seem non-conforming to the standard's requirements.)
2013-01-18use a common definition of NULL as 0L for C and C++Rich Felker-6/+1
the historical mess of having different definitions for C and C++ comes from the historical C definition as (void *)0 and the fact that (void *)0 can't be used in C++ because it does not convert to other pointer types implicitly. however, using plain 0 in C++ exposed bugs in C++ programs that call variadic functions with NULL as an argument and (wrongly; this is UB) expect it to arrive as a null pointer. on 64-bit machines, the high bits end up containing junk. glibc dodges the issue by using a GCC extension __null to define NULL; this is observably non-conforming because a conforming application could observe the definition of NULL via stringizing and see that it is neither an integer constant expression with value zero nor such an expression cast to void. switching to 0L eliminates the issue and provides compatibility with broken applications, since on all musl targets, long and pointers have the same size, representation, and argument-passing convention. we could maintain separate C and C++ definitions of NULL (i.e. just use 0L on C++ and use (void *)0 on C) but after careful analysis, it seems extremely difficult for a C program to even determine whether NULL has integer or pointer type, much less depend in subtle, unintentional ways, on whether it does. C89 seems to have no way to make the distinction. on C99, the fact that (int)(void *)0 is not an integer constant expression, along with subtle VLA/sizeof semantics, can be used to make the distinction, but many compilers are non-conforming and give the wrong result to this test anyway. on C11, _Generic can trivially make the distinction, but it seems unlikely that code targetting C11 would be so backwards in caring which definition of NULL an implementation uses. as such, the simplest path of using the same definition for NULL in both C and C++ was chosen. the #undef directive was also removed so that the compiler can catch and give a warning or error on redefinition if buggy programs have defined their own versions of NULL prior to inclusion of standard headers.
2012-12-03feature test macros: make _GNU_SOURCE enable everythingRich Felker-3/+0
previously, a few BSD features were enabled only by _BSD_SOURCE, not by _GNU_SOURCE. since _BSD_SOURCE is default in the absence of other feature test macros, this made adding _GNU_SOURCE to a project not a purely additive feature test macro; it actually caused some features to be suppressed. most of the changes made by this patch actually bring musl in closer alignment with the glibc behavior for _GNU_SOURCE. the only exceptions are the added visibility of functions like strlcpy which were BSD-only due to being disliked/rejected by glibc maintainers. here, I feel the consistency of having _GNU_SOURCE mean "everything", and especially the property of it being purely additive, are more valuable than hiding functions which glibc does not have.
2012-10-15add memmem function (gnu extension)Rich Felker-0/+1
based on strstr. passes gnulib tests and a few quick checks of my own.
2012-09-13strsep is BSD|GNU, not GNU-only; it's originally from BSDRich Felker-1/+4
2012-09-07default features: make musl usable without feature test macrosRich Felker-5/+1
the old behavior of exposing nothing except plain ISO C can be obtained by defining __STRICT_ANSI__ or using a compiler option (such as -std=c99) that predefines it. the new default featureset is POSIX with XSI plus _BSD_SOURCE. any explicit feature test macros will inhibit the default. installation docs have also been updated to reflect this change.
2012-09-06use restrict everywhere it's required by c99 and/or posix 2008Rich Felker-12/+18
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
2012-05-22support _BSD_SOURCE feature test macroRich Felker-5/+12
patch by Isaac Dunham. matched closely (maybe not exact) to glibc's idea of what _BSD_SOURCE should make visible.
2012-05-09omit declaration of basename wrongly interpreted as prototype in C++Rich Felker-0/+2
the non-prototype declaration of basename in string.h is an ugly compromise to avoid breaking 2 types of broken software: 1. programs which assume basename is declared in string.h and thus would suffer from dangerous pointer-truncation if an implicit declaration were used. 2. programs which include string.h with _GNU_SOURCE defined but then declare their own prototype for basename using the incorrect GNU signature for the function (which would clash with a correct prototype). however, since C++ does not have non-prototype declarations and interprets them as prototypes for a function with no arguments, we must omit it when compiling C++ code. thankfully, all known broken apps that suffer from the above issues are written in C, not C++.
2012-02-24replace prototype for basename in string.h with non-prototype declarationRich Felker-1/+1
GNU programs may expect the GNU version of basename, which has a different prototype (argument is const-qualified) and prototype it themselves too. of course if they're expecting the GNU behavior for the function, they'll still run into problems, but at least this eliminates some compile-time failures.
2012-02-07declare basename in string.h when _GNU_SOURCE is definedRich Felker-0/+1
note that it still will have the standards-conformant behavior, not the GNU behavior. but at least this prevents broken code from ending up with truncated pointers due to implicit declarations...
2012-02-06more locale_t interfaces (string stuff) and header updatesRich Felker-0/+8
this should be everything except for some functions where the non-_l version isn't even implemented yet (mainly some non-ISO-C wcs* functions).
2011-09-11add dummied strverscmp (obnoxious GNU function)Rich Felker-0/+1
programs that use this tend to horribly botch international text support, so it's questionable whether we want to support it even in the long term... for now, it's just a dummy that calls strcmp.
2011-04-26function signature fix: add const qualifier to mempcpy src argRich Felker-1/+1
2011-04-26typo in prototype for mempcpyRich Felker-1/+1
2011-04-26prototype for mempcpyRich Felker-0/+1
2011-04-13implement memrchr (nonstandard) and optimize strrchr in terms of itRich Felker-0/+1
2011-04-06fix prototype for strsepRich Felker-1/+1
2011-03-30add some missing prototypes for nonstandard functions (strsep, clearenv)Rich Felker-0/+1
2011-02-26fix missing prototype for strsignalRich Felker-0/+1
2011-02-24apply feature test protection to memccpyRich Felker-1/+4
2011-02-15prototype for gnu strcasestr (currently a stub)Rich Felker-0/+1
2011-02-14more header cleanup and conformance fixes - string.hRich Felker-7/+12
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+72