[PATCH 3.5/3] add memmem()
- From
René Scharfe <rene.scharfe@lsrfire.ath.cx>
- Date
- Sep 6, 2007, 22:32 UTC
- Message-ID
- <46E08016.9030604@lsrfire.ath.cx>
- In-Reply-To
- <46E028B9.2090908@lsrfire.ath.cx>
memmem() is a nice GNU extension for searching a length limited string in another one.
This compat version is based on the version found in glibc 2.2 (GPL 2); I only removed the optimization of checking the first char by hand, and generally tried to keep the code simple. We can add it back if memcmp shows up high in a profile, but for now I prefer to keep it (almost trivially) simple.
Since I don't really know which platforms beside those with a glibc have their own memmem(), I used a heuristic: if NO_STRCASESTR is set, then NO_MEMMEM is set, too.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> --- Makefile | 11 +++++++++++ compat/memmem.c | 29 +++++++++++++++++++++++++++++ git-compat-util.h | 6 ++++++ 3 files changed, 46 insertions(+), 0 deletions(-) create mode 100644 compat/memmem.c
diff --git a/Makefile b/Makefile index 51af531..bae073f 100644 --- a/Makefile +++ b/Makefile @@ -28,6 +28,8 @@ all:: # # Define NO_STRCASESTR if you don't have strcasestr. # +# Define NO_MEMMEM if you don't have memmem. +# # Define NO_STRLCPY if you don't have strlcpy. # # Define NO_STRTOUMAX if you don't have strtoumax in the C library. @@ -402,6 +404,7 @@ ifeq ($(uname_S),SunOS) NEEDS_NSL = YesPlease SHELL_PATH = /bin/bash NO_STRCASESTR = YesPlease + NO_MEMMEM = YesPlease NO_HSTRERROR = YesPlease ifeq ($(uname_R),5.8) NEEDS_LIBICONV = YesPlease @@ -424,6 +427,7 @@ ifeq ($(uname_O),Cygwin) NO_D_TYPE_IN_DIRENT = YesPlease NO_D_INO_IN_DIRENT = YesPlease NO_STRCASESTR = YesPlease + NO_MEMMEM = YesPlease NO_SYMLINK_HEAD = YesPlease NEEDS_LIBICONV = YesPlease NO_FAST_WORKING_DIRECTORY = UnfortunatelyYes @@ -442,6 +446,7 @@ ifeq ($(uname_S),FreeBSD) endif ifeq ($(uname_S),OpenBSD) NO_STRCASESTR = YesPlease + NO_MEMMEM = YesPlease NEEDS_LIBICONV = YesPlease BASIC_CFLAGS += -I/usr/local/include BASIC_LDFLAGS += -L/usr/local/lib @@ -456,6 +461,7 @@ ifeq ($(uname_S),NetBSD) endif ifeq ($(uname_S),AIX) NO_STRCASESTR=YesPlease + NO_MEMMEM = YesPlease NO_STRLCPY = YesPlease NEEDS_LIBICONV=YesPlease endif @@ -467,6 +473,7 @@ ifeq ($(uname_S),IRIX64) NO_IPV6=YesPlease NO_SETENV=YesPlease NO_STRCASESTR=YesPlease + NO_MEMMEM = YesPlease NO_STRLCPY = YesPlease NO_SOCKADDR_STORAGE=YesPlease SHELL_PATH=/usr/gnu/bin/bash @@ -661,6 +668,10 @@ ifdef NO_HSTRERROR COMPAT_CFLAGS += -DNO_HSTRERROR COMPAT_OBJS += compat/hstrerror.o endif +ifdef NO_MEMMEM + COMPAT_CFLAGS += -DNO_MEMMEM + COMPAT_OBJS += compat/memmem.o +endif ifeq ($(TCLTK_PATH),) NO_TCLTK=NoThanks diff --git a/compat/memmem.c b/compat/memmem.c new file mode 100644 index 0000000..cd0d877 --- /dev/null +++ b/compat/memmem.c @@ -0,0 +1,29 @@ +#include "../git-compat-util.h" + +void *gitmemmem(const void *haystack, size_t haystack_len, + const void *needle, size_t needle_len) +{ + const char *begin = haystack; + const char *last_possible = begin + haystack_len - needle_len; + + /* + * The first occurrence of the empty string is deemed to occur at + * the beginning of the string. + */ + if (needle_len == 0) + return (void *)begin; + + /* + * Sanity check, otherwise the loop might search through the whole + * memory. + */ + if (haystack_len < needle_len) + return NULL; + + for (; begin <= last_possible; begin++) { + if (!memcmp(begin, needle, needle_len)) + return (void *)begin; + } + + return NULL; +} diff --git a/git-compat-util.h b/git-compat-util.h index ca0a597..1bfbdeb 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -172,6 +172,12 @@ extern uintmax_t gitstrtoumax(const char *, char **, int); extern const char *githstrerror(int herror); #endif +#ifdef NO_MEMMEM +#define memmem gitmemmem +void *gitmemmem(const void *haystack, size_t haystacklen, + const void *needle, size_t needlelen); +#endif + extern void release_pack_memory(size_t, int); static inline char* xstrdup(const char *str)
-- 1.5.3