From d9390de638cd9788090c6299273a41a8cfa0b499 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Mon, 7 Feb 2022 17:23:43 +0100 Subject: [PATCH] tools/nolibc/string: add tiny versions of strncat() and strlcat() While these functions are often dangerous, forcing the user to work around their absence is often much worse. Let's provide small versions of each of them. The respective sizes in bytes on a few architectures are: strncat(): x86:0x33 mips:0x68 arm:0x3c strlcat(): x86:0x25 mips:0x4c arm:0x2c The two are quite different, and strncat() is even different from strncpy() in that it limits the amount of data it copies and will always terminate the output by one zero, while strlcat() will always limit the total output to the specified size and will put a zero if possible. Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney --- tools/include/nolibc/string.h | 41 +++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h index 7c274efcdfae..c550c9ba8f4c 100644 --- a/tools/include/nolibc/string.h +++ b/tools/include/nolibc/string.h @@ -121,6 +121,28 @@ size_t nolibc_strlen(const char *str) nolibc_strlen((str)); \ }) +static __attribute__((unused)) +size_t strlcat(char *dst, const char *src, size_t size) +{ + size_t len; + char c; + + for (len = 0; dst[len]; len++) + ; + + for (;;) { + c = *src; + if (len < size) + dst[len] = c; + if (!c) + break; + len++; + src++; + } + + return len; +} + static __attribute__((unused)) size_t strlcpy(char *dst, const char *src, size_t size) { @@ -138,6 +160,25 @@ size_t strlcpy(char *dst, const char *src, size_t size) return len; } +static __attribute__((unused)) +char *strncat(char *dst, const char *src, size_t size) +{ + char *orig = dst; + + while (*dst) + dst++; + + while (size && (*dst = *src)) { + src++; + dst++; + size--; + } + + *dst = 0; + return orig; +} + + static __attribute__((unused)) char *strncpy(char *dst, const char *src, size_t size) {