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[4/5] CODING_STYLE: add string management rules

Message ID AANLkTikdPo6xJC1y_pmXneTdytLB9i+dREF=3gFSGsFP@mail.gmail.com
State New
Headers show

Commit Message

Blue Swirl Aug. 12, 2010, 5:50 p.m. UTC 
Add string management rules, somewhat like libvirt HACKING.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
---
 CODING_STYLE |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

+instead of plain strdup/strndup.
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Patch

diff --git a/CODING_STYLE b/CODING_STYLE
index 085c86f..b230a01 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -156,3 +156,27 @@  Use of the malloc/free/realloc/calloc 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.
+
+8. 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