From d241f143c95861f46f7b75de96a8a3276517a14f Mon Sep 17 00:00:00 2001 From: Blue Swirl Date: Fri, 10 Sep 2010 18:53:05 +0000 Subject: HACKING: add string management rules Add string management rules, somewhat like libvirt HACKING. Signed-off-by: Blue Swirl --- HACKING | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'HACKING') diff --git a/HACKING b/HACKING index da0c1e84e6..3ad87aa362 100644 --- a/HACKING +++ b/HACKING @@ -86,3 +86,27 @@ that qemu_malloc() call with zero size is not allowed. Memory allocated by qemu_vmalloc or qemu_memalign must be freed with qemu_vfree, since breaking this will cause problems on Win32 and user emulators. + +4. String manipulation + +Do not use the strncpy function. According to the man page, it does +*not* guarantee a NULL-terminated buffer, which makes it extremely dangerous +to use. Instead, use functionally equivalent function: +void pstrcpy(char *buf, int buf_size, const char *str) + +Don't use strcat because it can't check for buffer overflows, but: +char *pstrcat(char *buf, int buf_size, const char *s) + +The same limitation exists with sprintf and vsprintf, so use snprintf and +vsnprintf. + +QEMU provides other useful string functions: +int strstart(const char *str, const char *val, const char **ptr) +int stristart(const char *str, const char *val, const char **ptr) +int qemu_strnlen(const char *s, int max_len) + +There are also replacement character processing macros for isxyz and toxyz, +so instead of e.g. isalnum you should use qemu_isalnum. + +Because of the memory management rules, you must use qemu_strdup/qemu_strndup +instead of plain strdup/strndup. -- cgit v1.2.3