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Fix access violations when cloning/fetching via HTTPS #38

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Merged
merged 3 commits into from
Mar 20, 2015
Merged

Fix access violations when cloning/fetching via HTTPS #38

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f07ccbd
UTF-8 environment: be a little bit more defensive
dscho Mar 17, 2015
ab16d5e
mingw: be more defensive when making the environment block
dscho Mar 18, 2015
22cc9c9
mingw: be *very* wary about outside environment changes
dscho Mar 17, 2015
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65 changes: 58 additions & 7 deletions compat/mingw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -966,6 +966,10 @@ static int do_putenv(char **env, const char *name, int size, int free_old);
static int environ_size = 0;
/* allocated size of environ array, in bytes */
static int environ_alloc = 0;
/* used as a indicator when the environment has been changed outside mingw.c */
static char **saved_environ;

static void maybe_reinitialize_environ(void);

/*
* Create environment block suitable for CreateProcess. Merges current
Expand All @@ -975,21 +979,24 @@ static wchar_t *make_environment_block(char **deltaenv)
{
wchar_t *wenvblk = NULL;
char **tmpenv;
int i = 0, size = environ_size, wenvsz = 0, wenvpos = 0;
int i = 0, size, wenvsz = 0, wenvpos = 0;

maybe_reinitialize_environ();
size = environ_size;

while (deltaenv && deltaenv[i])
while (deltaenv && deltaenv[i] && *deltaenv[i])
i++;

/* 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 (i = 0; deltaenv && deltaenv[i]; i++)
for (i = 0; deltaenv && deltaenv[i] && *deltaenv[i]; i++)
size = do_putenv(tmpenv, deltaenv[i], size, 0);

/* create environment block from temporary environment */
for (i = 0; tmpenv[i]; i++) {
for (i = 0; tmpenv[i] && *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], tmpenv[i], size) + 1;
Expand Down Expand Up @@ -1278,6 +1285,41 @@ static int compareenv(const void *v1, const void *v2)
}
}

/*
* Functions implemented outside Git are able to modify the environment,
* too. For example, cURL's curl_global_init() function sets the CHARSET
* environment variable (at least in certain circumstances).
*
* Therefore we need to be *really* careful *not* to assume that we have
* sole control over the environment and reinitalize it when necessary.
*/
static void maybe_reinitialize_environ(void)
{
int i;

if (!saved_environ) {
warning("MinGW environment not initialized yet");
return;
}

if (environ_size <= 0)
return;

if (saved_environ != environ)
/* We have *no* idea how much space was allocated outside */
environ_alloc = 0;
else if (!environ[environ_size - 1])
return; /* still consistent */

for (i = 0; environ[i] && *environ[i]; i++)
; /* continue counting */
environ[i] = NULL;
environ_size = i + 1;

/* sort environment for O(log n) getenv / putenv */
qsort(environ, i, sizeof(char*), compareenv);
}

static int bsearchenv(char **env, const char *name, size_t size)
{
unsigned low = 0, high = size;
Expand All @@ -1301,7 +1343,7 @@ static int bsearchenv(char **env, const char *name, size_t size)
*/
static int do_putenv(char **env, const char *name, int size, int free_old)
{
int i = bsearchenv(env, name, size - 1);
int i = size <= 0 ? -1 : bsearchenv(env, name, size - 1);

/* optionally free removed / replaced entry */
if (i >= 0 && free_old)
Expand All @@ -1326,7 +1368,14 @@ static int do_putenv(char **env, const char *name, int size, int free_old)
char *mingw_getenv(const char *name)
{
char *value;
int pos = bsearchenv(environ, name, environ_size - 1);
int pos;

if (environ_size <= 0)
return NULL;

maybe_reinitialize_environ();
pos = bsearchenv(environ, name, environ_size - 1);

if (pos < 0)
return NULL;
value = strchr(environ[pos], '=');
Expand All @@ -1335,7 +1384,9 @@ char *mingw_getenv(const char *name)

int mingw_putenv(const char *namevalue)
{
maybe_reinitialize_environ();
ALLOC_GROW(environ, (environ_size + 1) * sizeof(char*), environ_alloc);
saved_environ = environ;
environ_size = do_putenv(environ, namevalue, environ_size, 1);
return 0;
}
Expand Down Expand Up @@ -2223,7 +2274,7 @@ void mingw_startup()
*/
environ_size = i + 1;
environ_alloc = alloc_nr(environ_size * sizeof(char*));
environ = malloc_startup(environ_alloc);
saved_environ = environ = malloc_startup(environ_alloc);

/* allocate buffer (wchar_t encodes to max 3 UTF-8 bytes) */
maxlen = 3 * maxlen + 1;
Expand Down