Re: [libvirt] [PATCH v3 03/19] util: use glib memory allocation functions

Convert the VIR_ALLOC family of APIs with use of the g_malloc family of APIs. Use of VIR_ALLOC related functions should be incrementally phased out over time, allowing return value checks to be dropped. Use of VIR_FREE should be replaced with auto-cleanup whenever possible. We previously used the 'calloc-posix' gnulib module because mingw does not set errno to ENOMEM on failure. Reviewed-by: Ján Tomko <jtomko(a)redhat.com&gt; Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- bootstrap.conf | 1 - docs/hacking.html.in | 106 +++++-------------------------------------- src/util/viralloc.c | 29 +++--------- src/util/viralloc.h | 9 ++++ 4 files changed, 27 insertions(+), 118 deletions(-) diff --git a/bootstrap.conf b/bootstrap.conf index 358d783a6b..7d73584809 100644 --- a/bootstrap.conf +++ b/bootstrap.conf @@ -26,7 +26,6 @@ byteswap c-ctype c-strcase c-strcasestr -calloc-posix canonicalize-lgpl chown clock-time diff --git a/docs/hacking.html.in b/docs/hacking.html.in index 2e064ced5e..8072796312 100644 --- a/docs/hacking.html.in +++ b/docs/hacking.html.in @@ -1008,102 +1008,20 @@ BAD: </p> <dl> + <dt>VIR_ALLOC, VIR_REALLOC, VIR_RESIZE_N, VIR_EXPAND_N, + VIR_SHRINK_N, VIR_FREE, VIR_APPEND_ELEMENT, VIR_INSERT_ELEMENT, + VIR_DELETE_ELEMENT</dt> + <dd>Prefer the GLib APIs g_new0/g_renew/g_free in most cases. + There should rarely be a need to use g_malloc/g_realloc. + Instead of using plain C arrays, it is preferrable to use + one of the GLib types, GArray, GPtrArray or GByteArray. These + all use a struct to track the array memory and size together + and efficiently resize. <strong>NEVER MIX</strong> use of the + classic libvirt memory allocation APIs and GLib APIs within + a single method. Keep the style consistent, converting existing + code to GLib style in a separate, prior commit.</dd> </dl> - <h2><a id="memalloc">Low level memory management</a></h2> - - <p> - Use of the malloc/free/realloc/calloc APIs is deprecated in the libvirt - codebase, because they encourage a number of serious coding bugs and do - not enable compile time verification of checks for NULL. Instead of these - routines, use the macros from viralloc.h. - </p> - - <ul> - <li><p>To allocate a single object:</p> - -<pre> - virDomainPtr domain; - - if (VIR_ALLOC(domain) &lt; 0) - return NULL; -</pre> - </li> - - <li><p>To allocate an array of objects:</p> -<pre> - virDomainPtr domains; - size_t ndomains = 10; - - if (VIR_ALLOC_N(domains, ndomains) &lt; 0) - return NULL; -</pre> - </li> - - <li><p>To allocate an array of object pointers:</p> -<pre> - virDomainPtr *domains; - size_t ndomains = 10; - - if (VIR_ALLOC_N(domains, ndomains) &lt; 0) - return NULL; -</pre> - </li> - - <li><p>To re-allocate the array of domains to be 1 element - longer (however, note that repeatedly expanding an array by 1 - scales quadratically, so this is recommended only for smaller - arrays):</p> -<pre> - virDomainPtr domains; - size_t ndomains = 0; - - if (VIR_EXPAND_N(domains, ndomains, 1) &lt; 0) - return NULL; - domains[ndomains - 1] = domain; -</pre></li> - - <li><p>To ensure an array has room to hold at least one more - element (this approach scales better, but requires tracking - allocation separately from usage)</p> - -<pre> - virDomainPtr domains; - size_t ndomains = 0; - size_t ndomains_max = 0; - - if (VIR_RESIZE_N(domains, ndomains_max, ndomains, 1) &lt; 0) - return NULL; - domains[ndomains++] = domain; -</pre> - </li> - - <li><p>To trim an array of domains from its allocated size down - to the actual used size:</p> - -<pre> - virDomainPtr domains; - size_t ndomains = x; - size_t ndomains_max = y; - - VIR_SHRINK_N(domains, ndomains_max, ndomains_max - ndomains); -</pre></li> - - <li><p>To free an array of domains:</p> -<pre> - virDomainPtr domains; - size_t ndomains = x; - size_t ndomains_max = y; - size_t i; - - for (i = 0; i &lt; ndomains; i++) - VIR_FREE(domains[i]); - VIR_FREE(domains); - ndomains_max = ndomains = 0; -</pre> - </li> - </ul> - <h2><a id="file_handling">File handling</a></h2> <p> diff --git a/src/util/viralloc.c b/src/util/viralloc.c index 10a8d0fb73..b8ca850764 100644 --- a/src/util/viralloc.c +++ b/src/util/viralloc.c @@ -45,10 +45,7 @@ VIR_LOG_INIT("util.alloc"); int virAlloc(void *ptrptr, size_t size) { - *(void **)ptrptr = calloc(1, size); - if (*(void **)ptrptr == NULL) - abort(); - + *(void **)ptrptr = g_malloc0(size); return 0; } @@ -69,10 +66,7 @@ int virAllocN(void *ptrptr, size_t size, size_t count) { - *(void**)ptrptr = calloc(count, size); - if (*(void**)ptrptr == NULL) - abort(); - + *(void**)ptrptr = g_malloc0_n(count, size); return 0; } @@ -94,16 +88,7 @@ int virReallocN(void *ptrptr, size_t size, size_t count) { - void *tmp; - - if (xalloc_oversized(count, size)) - abort(); - - tmp = realloc(*(void**)ptrptr, size * count); - if (!tmp && ((size * count) != 0)) - abort(); - - *(void**)ptrptr = tmp; + *(void **)ptrptr = g_realloc_n(*(void**)ptrptr, size, count); return 0; } @@ -343,9 +328,7 @@ int virAllocVar(void *ptrptr, abort(); alloc_size = struct_size + (element_size * count); - *(void **)ptrptr = calloc(1, alloc_size); - if (*(void **)ptrptr == NULL) - abort(); + *(void **)ptrptr = g_malloc0(alloc_size); return 0; } @@ -362,7 +345,7 @@ void virFree(void *ptrptr) { int save_errno = errno; - free(*(void**)ptrptr); + g_free(*(void**)ptrptr);

errno = save_errno; } @@ -395,7 +378,7 @@ void virDispose(void *ptrptr, if (*(void**)ptrptr && count > 0) memset(*(void **)ptrptr, 0, count * element_size); - free(*(void**)ptrptr); + g_free(*(void**)ptrptr); *(void**)ptrptr = NULL; if (countptr) diff --git a/src/util/viralloc.h b/src/util/viralloc.h index 3e72e40bc9..517f9aada6 100644 --- a/src/util/viralloc.h +++ b/src/util/viralloc.h @@ -24,6 +24,15 @@ #include "internal.h" +/** + * DEPRECATION WARNING + * + * APIs in this file should only be used when modifying existing code. + * Consider converting existing code to use the new APIs when touching + * it. All new code must use the GLib memory allocation APIs and/or + * GLib array data types. See the hacking file for more guidance. + */ + /* Return 1 if an array of N objects, each of size S, cannot exist due to size arithmetic overflow. S must be positive and N must be nonnegative. This is a macro, not an inline function, so that it -- 2.21.0 -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list