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grep: make PCRE2 aware of custom allocator 

94da9193a6 (grep: add support for PCRE v2, 2017-06-01) didn't include
a way to override the system allocator, and so it is incompatible with
custom allocators (e.g. nedmalloc). This problem became obvious when we
tried to plug a memory leak by `free()`ing a data structure allocated by
PCRE2, triggering a segfault in Windows (where we use nedmalloc by
default).

PCRE2 requires the use of a general context to override the allocator
and therefore, there is a lot more code needed than in PCRE1, including
a couple of wrapper functions.

Extend the grep API with a "destructor" that could be called to cleanup
any objects that were created and used globally.

Update `builtin/grep.c` to use that new API, but any other future users
should make sure to have matching `grep_init()`/`grep_destroy()` calls
if they are using the pattern matching functionality.

Move some of the logic that was before done per thread (in the workers)
into an earlier phase to avoid degrading performance, but as the use of
PCRE2 with custom allocators is better understood it is expected more of
its functions will be instructed to use the custom allocator as well as
was done in the original code[1] this work was based on.

[1] https://public-inbox.org/git/3397e6797f872aedd18c6d795f4976e1c579514b.1565005867.git.gitgitgadget@gmail.com/

Reported-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Carlo Marcelo Arenas Belón 2019-10-16 12:10:23 +00:00 committed by Junio C Hamano
parent 57d4660468
commit 513f2b0bbd
3 changed files with 35 additions and 1 deletions
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1
builtin/grep.c
View File

@ -1145,5 +1145,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
run_pager(&opt, prefix);
clear_pathspec(&pathspec);
free_grep_patterns(&opt);
grep_destroy();
return !hit;
}

34
grep.c
View File

@ -16,6 +16,20 @@ static int grep_source_is_binary(struct grep_source *gs,
static struct grep_opt grep_defaults;
#ifdef USE_LIBPCRE2
static pcre2_general_context *pcre2_global_context;
static void *pcre2_malloc(PCRE2_SIZE size, MAYBE_UNUSED void *memory_data)
{
return malloc(size);
}
static void pcre2_free(void *pointer, MAYBE_UNUSED void *memory_data)
{
return free(pointer);
}
#endif
static const char *color_grep_slots[] = {
[GREP_COLOR_CONTEXT] = "context",
[GREP_COLOR_FILENAME] = "filename",
@ -153,12 +167,20 @@ int grep_config(const char *var, const char *value, void *cb)
*
* If using PCRE, make sure that the library is configured
* to use the same allocator as Git (e.g. nedmalloc on Windows).
*
* Any allocated memory needs to be released in grep_destroy().
*/
void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix)
{
struct grep_opt *def = &grep_defaults;
int i;
#if defined(USE_LIBPCRE2)
if (!pcre2_global_context)
pcre2_global_context = pcre2_general_context_create(
pcre2_malloc, pcre2_free, NULL);
#endif
#ifdef USE_LIBPCRE1
pcre_malloc = malloc;
pcre_free = free;
@ -186,6 +208,13 @@ void grep_init(struct grep_opt *opt, struct repository *repo, const char *prefix
color_set(opt->colors[i], def->colors[i]);
}
void grep_destroy(void)
{
#ifdef USE_LIBPCRE2
pcre2_general_context_free(pcre2_global_context);
#endif
}
static void grep_set_pattern_type_option(enum grep_pattern_type pattern_type, struct grep_opt *opt)
{
/*
@ -505,9 +534,12 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
p->pcre2_compile_context = NULL;
/* pcre2_global_context is initialized in append_grep_pattern */
if (opt->ignore_case) {
if (has_non_ascii(p->pattern)) {
character_tables = pcre2_maketables(NULL);
if (!pcre2_global_context)
BUG("pcre2_global_context uninitialized");
character_tables = pcre2_maketables(pcre2_global_context);
p->pcre2_compile_context = pcre2_compile_context_create(NULL);
pcre2_set_character_tables(p->pcre2_compile_context, character_tables);
}

1
grep.h
View File

@ -189,6 +189,7 @@ struct grep_opt {
void init_grep_defaults(struct repository *);
int grep_config(const char *var, const char *value, void *);
void grep_init(struct grep_opt *, struct repository *repo, const char *prefix);
void grep_destroy(void);
void grep_commit_pattern_type(enum grep_pattern_type, struct grep_opt *opt);
void append_grep_pat(struct grep_opt *opt, const char *pat, size_t patlen, const char *origin, int no, enum grep_pat_token t);