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string: make VIR_STRDUP easier to use

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While reviewing proposed VIR_STRDUP conversions, I've already noticed
several places that do:

if (str && VIR_STRDUP(dest, str) < 0)

which can be simplified by allowing str to be NULL (something that
strdup() doesn't allow).  Meanwhile, code that wants to ensure a
non-NULL dest regardless of the source can check for <= 0.

Also, make it part of the VIR_STRDUP contract that macro arguments
are evaluated exactly once.

* src/util/virstring.h (VIR_STRDUP, VIR_STRDUP_QUIET, VIR_STRNDUP)
(VIR_STRNDUP_QUIET): Improve contract.
* src/util/virstring.c (virStrdup, virStrndup): Change return
conventions.
* docs/hacking.html.in: Document this.
* HACKING: Regenerate.

Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Eric Blake
2013-05-06 20:42:44 -06:00
parent ddcfc5492a
commit 6b74a9f5d9
4 changed files with 36 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
src/util/virstring.c
View File

@@ -532,7 +532,7 @@ virArgvToString(const char *const *argv)
* caller's body where virStrdup is called from. Consider
* using VIR_STRDUP which sets these automatically.
*
* Returns: 0 on success, -1 otherwise.
* Returns: 0 for NULL src, 1 on successful copy, -1 otherwise.
*/
int
virStrdup(char **dest,
@@ -543,13 +543,15 @@ virStrdup(char **dest,
const char *funcname,
size_t linenr)
{
if (!src)
return 0;
if (!(*dest = strdup(src))) {
if (report)
virReportOOMErrorFull(domcode, filename, funcname, linenr);
return -1;
}
return 0;
return 1;
}
/**
@@ -569,7 +571,7 @@ virStrdup(char **dest,
* caller's body where virStrndup is called from. Consider
* using VIR_STRNDUP which sets these automatically.
*
* Returns: 0 on success, -1 otherwise.
* Returns: 0 for NULL src, 1 on successful copy, -1 otherwise.
*/
int
virStrndup(char **dest,
@@ -581,11 +583,13 @@ virStrndup(char **dest,
const char *funcname,
size_t linenr)
{
if (!src)
return 0;
if (!(*dest = strndup(src, n))) {
if (report)
virReportOOMErrorFull(domcode, filename, funcname, linenr);
return -1;
}
return 0;
return 1;
}

22
src/util/virstring.h
View File

@@ -92,11 +92,11 @@ char *virStrcpy(char *dest, const char *src, size_t destbytes)
/* Don't call these directly - use the macros below */
int virStrdup(char **dest, const char *src, bool report, int domcode,
const char *filename, const char *funcname, size_t linenr)
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1);
int virStrndup(char **dest, const char *src, size_t n, bool report, int domcode,
const char *filename, const char *funcname, size_t linenr)
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
ATTRIBUTE_RETURN_CHECK ATTRIBUTE_NONNULL(1);
/**
* VIR_STRDUP:
@@ -105,7 +105,10 @@ int virStrndup(char **dest, const char *src, size_t n, bool report, int domcode,
*
* Duplicate @src string and store it into @dst.
*
* Returns -1 on failure (with OOM error reported), 0 on success
* This macro is safe to use on arguments with side effects.
*
* Returns -1 on failure (with OOM error reported), 0 if @src was NULL,
* 1 if @src was copied
*/
# define VIR_STRDUP(dst, src) virStrdup(&(dst), src, true, VIR_FROM_THIS, \
__FILE__, __FUNCTION__, __LINE__)
@@ -117,7 +120,9 @@ int virStrndup(char **dest, const char *src, size_t n, bool report, int domcode,
*
* Duplicate @src string and store it into @dst.
*
* Returns -1 on failure, 0 on success
* This macro is safe to use on arguments with side effects.
*
* Returns -1 on failure, 0 if @src was NULL, 1 if @src was copied
*/
# define VIR_STRDUP_QUIET(dst, src) virStrdup(&(dst), src, false, 0, NULL, NULL, 0)
@@ -130,7 +135,10 @@ int virStrndup(char **dest, const char *src, size_t n, bool report, int domcode,
* Duplicate @src string and store it into @dst. If @src is longer than @n,
* only @n bytes are copied and terminating null byte '\0' is added.
*
* Returns -1 on failure (with OOM error reported), 0 on success
* This macro is safe to use on arguments with side effects.
*
* Returns -1 on failure (with OOM error reported), 0 if @src was NULL,
* 1 if @src was copied
*/
# define VIR_STRNDUP(dst, src, n) virStrndup(&(dst), src, n, true, \
VIR_FROM_THIS, __FILE__, \
@@ -145,7 +153,9 @@ int virStrndup(char **dest, const char *src, size_t n, bool report, int domcode,
* Duplicate @src string and store it into @dst. If @src is longer than @n,
* only @n bytes are copied and terminating null byte '\0' is added.
*
* Returns -1 on failure, 0 on success
* This macro is safe to use on arguments with side effects.
*
* Returns -1 on failure, 0 if @src was NULL, 1 if @src was copied
*/
# define VIR_STRNDUP_QUIET(dst, src, n) virStrndup(&(dst), src, n, false, \
0, NULL, NULL, 0)