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v0.5.1
Revision ca1b4116483b397e78483376296bcd23916ab553 authored by Johannes Schindelin on 15 February 2019, 15:17:45 UTC, committed by Junio C Hamano on 15 February 2019, 18:25:28 UTC 
mingw: safe-guard a bit more against getenv() problems
 
Running up to v2.21.0, we fixed two bugs that were made prominent by the
Windows-specific change to retain copies of only the 30 latest getenv()
calls' returned strings, invalidating any copies of previous getenv()
calls' return values.

While this really shines a light onto bugs of the form where we hold
onto getenv()'s return values without copying them, it is also a real
problem for users.

And even if Jeff King's patches merged via 773e408881 (Merge branch
'jk/save-getenv-result', 2019-01-29) provide further work on that front,
we are far from done. Just one example: on Windows, we unset environment
variables when spawning new processes, which potentially invalidates
strings that were previously obtained via getenv(), and therefore we
have to duplicate environment values that are somehow involved in
spawning new processes (e.g. GIT_MAN_VIEWER in show_man_page()).

We do not have a chance to investigate, let address, all of those issues
in time for v2.21.0, so let's at least help Windows users by increasing
the number of getenv() calls' return values that are kept valid. The
number 64 was determined by looking at the average number of getenv()
calls per process in the entire test suite run on Windows (which is
around 40) and then adding a bit for good measure. And it is a power of
two (which would have hit yesterday's theme perfectly).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 2d08f3d
Raw File
oidmap.c 
#include "cache.h"
#include "oidmap.h"

static int oidmap_neq(const void *hashmap_cmp_fn_data,
		      const void *entry, const void *entry_or_key,
		      const void *keydata)
{
	const struct oidmap_entry *entry_ = entry;
	if (keydata)
		return !oideq(&entry_->oid, (const struct object_id *) keydata);
	return !oideq(&entry_->oid,
		      &((const struct oidmap_entry *) entry_or_key)->oid);
}

static int hash(const struct object_id *oid)
{
	int hash;
	memcpy(&hash, oid->hash, sizeof(hash));
	return hash;
}

void oidmap_init(struct oidmap *map, size_t initial_size)
{
	hashmap_init(&map->map, oidmap_neq, NULL, initial_size);
}

void oidmap_free(struct oidmap *map, int free_entries)
{
	if (!map)
		return;
	hashmap_free(&map->map, free_entries);
}

void *oidmap_get(const struct oidmap *map, const struct object_id *key)
{
	if (!map->map.cmpfn)
		return NULL;

	return hashmap_get_from_hash(&map->map, hash(key), key);
}

void *oidmap_remove(struct oidmap *map, const struct object_id *key)
{
	struct hashmap_entry entry;

	if (!map->map.cmpfn)
		oidmap_init(map, 0);

	hashmap_entry_init(&entry, hash(key));
	return hashmap_remove(&map->map, &entry, key);
}

void *oidmap_put(struct oidmap *map, void *entry)
{
	struct oidmap_entry *to_put = entry;

	if (!map->map.cmpfn)
		oidmap_init(map, 0);

	hashmap_entry_init(&to_put->internal_entry, hash(&to_put->oid));
	return hashmap_put(&map->map, to_put);
}
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