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Win32: reduce environment array reallocations

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Move environment array reallocation from do_putenv to the respective
callers. Keep track of the environment size in a global variable. Use
ALLOC_GROW in mingw_putenv to reduce reallocations. Allocate a
sufficiently sized environment array in make_environment_block to prevent
reallocations.

Signed-off-by: Karsten Blees <blees@dcon.de>
This commit is contained in:
Karsten Blees
2012-01-16 00:00:35 +01:00
committed by Pat Thoyts
parent 4fe9da7542
commit b30ca1b3ce
1 changed files with 34 additions and 26 deletions
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60
compat/mingw.c
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@@ -807,19 +807,19 @@ static int lookupenv(char **env, const char *name, size_t nmln)
/*
* If name contains '=', then sets the variable, otherwise it unsets it
* Size includes the terminating NULL. Env must have room for size + 1 entries
* (in case of insert). Returns the new size. Optionally frees removed entries.
*/
static char **do_putenv(char **env, const char *name, int free_old)
static int do_putenv(char **env, const char *name, int size, int free_old)
{
char *eq = strchrnul(name, '=');
int i = lookupenv(env, name, eq-name);
if (i < 0) {
if (*eq) {
for (i = 0; env[i]; i++)
;
env = xrealloc(env, (i+2)*sizeof(*env));
env[i] = (char*) name;
env[i+1] = NULL;
env[size - 1] = (char*) name;
env[size] = NULL;
size++;
}
}
else {
@@ -827,13 +827,20 @@ static char **do_putenv(char **env, const char *name, int free_old)
free(env[i]);
if (*eq)
env[i] = (char*) name;
else
else {
for (; env[i]; i++)
env[i] = env[i+1];
size--;
}
}
return env;
return size;
}
/* used number of elements of environ array, including terminating NULL */
static int environ_size = 0;
/* allocated size of environ array, in bytes */
static int environ_alloc = 0;
#undef getenv
char *mingw_getenv(const char *name)
{
@@ -853,7 +860,8 @@ char *mingw_getenv(const char *name)
int mingw_putenv(const char *namevalue)
{
environ = do_putenv(environ, namevalue, 1);
ALLOC_GROW(environ, (environ_size + 1) * sizeof(char*), environ_alloc);
environ_size = do_putenv(environ, namevalue, environ_size, 1);
return 0;
}
@@ -1052,31 +1060,28 @@ static char *path_lookup(const char *cmd, char **path, int exe_only)
static wchar_t *make_environment_block(char **deltaenv)
{
wchar_t *wenvblk = NULL;
int count = 0;
char **e, **tmpenv;
int size = 0, wenvsz = 0, wenvpos = 0;
char **tmpenv;
int i = 0, size = environ_size, wenvsz = 0, wenvpos = 0;
while (environ[count])
count++;
while (deltaenv && deltaenv[i])
i++;
/* copy the environment */
tmpenv = xmalloc(sizeof(*tmpenv) * (count + 1));
memcpy(tmpenv, environ, sizeof(*tmpenv) * (count + 1));
/* copy the environment, leaving space for changes */
tmpenv = xmalloc((size + i) * sizeof(char*));
memcpy(tmpenv, environ, size * sizeof(char*));
/* merge supplied environment changes into the temporary environment */
for (e = deltaenv; e && *e; e++)
tmpenv = do_putenv(tmpenv, *e, 0);
for (i = 0; deltaenv && deltaenv[i]; i++)
size = do_putenv(tmpenv, deltaenv[i], size, 0);
/* environment must be sorted */
for (count = 0; tmpenv[count]; )
count++;
qsort(tmpenv, count, sizeof(*tmpenv), compareenv);
qsort(tmpenv, size - 1, sizeof(char*), compareenv);
/* create environment block from temporary environment */
for (e = tmpenv; *e; e++) {
size = 2 * strlen(*e) + 2; /* +2 for final \0 */
for (i = 0; tmpenv[i]; i++) {
size = 2 * strlen(tmpenv[i]) + 2; /* +2 for final \0 */
ALLOC_GROW(wenvblk, (wenvpos + size) * sizeof(wchar_t), wenvsz);
wenvpos += xutftowcs(&wenvblk[wenvpos], *e, size) + 1;
wenvpos += xutftowcs(&wenvblk[wenvpos], tmpenv[i], size) + 1;
}
/* add final \0 terminator */
wenvblk[wenvpos] = 0;
@@ -2136,7 +2141,9 @@ void mingw_startup()
maxlen = max(maxlen, wcslen(wenv[i]));
/* nedmalloc can't free CRT memory, allocate resizable environment list */
environ = xcalloc(i + 1, sizeof(char*));
environ = NULL;
environ_size = i + 1;
ALLOC_GROW(environ, environ_size * sizeof(char*), environ_alloc);
/* allocate buffer (wchar_t encodes to max 3 UTF-8 bytes) */
maxlen = 3 * maxlen + 1;
@@ -2153,6 +2160,7 @@ void mingw_startup()
len = xwcstoutf(buffer, wenv[i], maxlen);
environ[i] = xmemdupz(buffer, len);
}
environ[i] = NULL;
free(buffer);
/* initialize critical section for waitpid pinfo_t list */