coroutine-gthread.c: Avoid threading APIs deprecated in GLib 2.31

[qemu.git] / HACKING

diff --git a/HACKING b/HACKING
index da0c1e84e63465c00664c64b8a5edda3083348e0..471cf1d1970959e95ba18aa8abd798bb5240d95b 100644 (file)
--- a/HACKING
+++ b/HACKING
@@ -77,12 +77,48 @@ avoided.
 
 Use of the malloc/free/realloc/calloc/valloc/memalign/posix_memalign
 APIs is not allowed in the QEMU codebase. Instead of these routines,
-use the replacement qemu_malloc/qemu_mallocz/qemu_realloc/qemu_free or
-qemu_vmalloc/qemu_memalign/qemu_vfree APIs.
+use the GLib memory allocation routines g_malloc/g_malloc0/g_new/
+g_new0/g_realloc/g_free or QEMU's qemu_vmalloc/qemu_memalign/qemu_vfree
+APIs.
 
-Please note that NULL check for the qemu_malloc result is redundant and
-that qemu_malloc() call with zero size is not allowed.
+Please note that g_malloc will exit on allocation failure, so there
+is no need to test for failure (as you would have to with malloc).
+Calling g_malloc with a zero size is valid and will return NULL.
 
 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 g_strdup/g_strndup
+instead of plain strdup/strndup.
+
+5. Printf-style functions
+
+Whenever you add a new printf-style function, i.e., one with a format
+string argument and following "..." in its prototype, be sure to use
+gcc's printf attribute directive in the prototype.
+
+This makes it so gcc's -Wformat and -Wformat-security options can do
+their jobs and cross-check format strings with the number and types
+of arguments.