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authorJohannes Schindelin <johannes.schindelin@gmx.de>2018-10-30 09:22:30 (GMT)
committerJunio C Hamano <gitster@pobox.com>2018-10-31 02:43:14 (GMT)
commitfe21c6b285df4088f9685d5deed425064367ea24 (patch)
tree25b756a05aae6baac1561488b42c438e824bbc5d /compat/mingw.c
parent665177ebf2e948504dcb255d2f58817224a8935a (diff)
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mingw: reencode environment variables on the fly (UTF-16 <-> UTF-8)
On Windows, the authoritative environment is encoded in UTF-16. In Git for Windows, we convert that to UTF-8 (because UTF-16 is *such* a foreign idea to Git that its source code is unprepared for it). Previously, out of performance concerns, we converted the entire environment to UTF-8 in one fell swoop at the beginning, and upon putenv() and run_command() converted it back. Having a private copy of the environment comes with its own perils: when a library used by Git's source code tries to modify the environment, it does not really work (in Git for Windows' case, libcurl, see https://github.com/git-for-windows/git/compare/bcad1e6d58^...bcad1e6d58^2 for a glimpse of the issues). Hence, it makes our environment handling substantially more robust if we switch to on-the-fly-conversion in `getenv()`/`putenv()` calls. Based on an initial version in the MSVC context by Jeff Hostetler, this patch makes it so. Surprisingly, this has a *positive* effect on speed: at the time when the current code was written, we tested the performance, and there were *so many* `getenv()` calls that it seemed better to convert everything in one go. In the meantime, though, Git has obviously been cleaned up a bit with regards to `getenv()` calls so that the Git processes spawned by the test suite use an average of only 40 `getenv()`/`putenv()` calls over the process lifetime. Speaking of the entire test suite: the total time spent in the re-encoding in the current code takes about 32.4 seconds (out of 113 minutes runtime), whereas the code introduced in this patch takes only about 8.2 seconds in total. Not much, but it proves that we need not be concerned about the performance impact introduced by this patch. Helped-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'compat/mingw.c')
-rw-r--r--compat/mingw.c280
1 files changed, 168 insertions, 112 deletions
diff --git a/compat/mingw.c b/compat/mingw.c
index 858ca14..c1de85f 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1040,44 +1040,121 @@ static char *path_lookup(const char *cmd, int exe_only)
return prog;
}
-static int do_putenv(char **env, const char *name, int size, int free_old);
+static const wchar_t *wcschrnul(const wchar_t *s, wchar_t c)
+{
+ while (*s && *s != c)
+ s++;
+ return s;
+}
+
+/* Compare only keys */
+static int wenvcmp(const void *a, const void *b)
+{
+ wchar_t *p = *(wchar_t **)a, *q = *(wchar_t **)b;
+ size_t p_len, q_len;
+
+ /* Find the keys */
+ p_len = wcschrnul(p, L'=') - p;
+ q_len = wcschrnul(q, L'=') - q;
+
+ /* If the length differs, include the shorter key's NUL */
+ if (p_len < q_len)
+ p_len++;
+ else if (p_len > q_len)
+ p_len = q_len + 1;
+
+ return _wcsnicmp(p, q, p_len);
+}
-/* 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;
+/* We need a stable sort to convert the environment between UTF-16 <-> UTF-8 */
+#ifndef INTERNAL_QSORT
+#include "qsort.c"
+#endif
/*
- * Create environment block suitable for CreateProcess. Merges current
- * process environment and the supplied environment changes.
+ * Build an environment block combining the inherited environment
+ * merged with the given list of settings.
+ *
+ * Values of the form "KEY=VALUE" in deltaenv override inherited values.
+ * Values of the form "KEY" in deltaenv delete inherited values.
+ *
+ * Multiple entries in deltaenv for the same key are explicitly allowed.
+ *
+ * We return a contiguous block of UNICODE strings with a final trailing
+ * zero word.
*/
static wchar_t *make_environment_block(char **deltaenv)
{
- wchar_t *wenvblk = NULL;
- char **tmpenv;
- int i = 0, size = environ_size, wenvsz = 0, wenvpos = 0;
+ wchar_t *wenv = GetEnvironmentStringsW(), *wdeltaenv, *result, *p;
+ size_t wlen, s, delta_size, size;
+
+ wchar_t **array = NULL;
+ size_t alloc = 0, nr = 0, i;
+
+ size = 1; /* for extra NUL at the end */
+
+ /* If there is no deltaenv to apply, simply return a copy. */
+ if (!deltaenv || !*deltaenv) {
+ for (p = wenv; p && *p; ) {
+ size_t s = wcslen(p) + 1;
+ size += s;
+ p += s;
+ }
+
+ ALLOC_ARRAY(result, size);
+ memcpy(result, wenv, size * sizeof(*wenv));
+ FreeEnvironmentStringsW(wenv);
+ return result;
+ }
+
+ /*
+ * If there is a deltaenv, let's accumulate all keys into `array`,
+ * sort them using the stable git_qsort() and then copy, skipping
+ * duplicate keys
+ */
+ for (p = wenv; p && *p; ) {
+ ALLOC_GROW(array, nr + 1, alloc);
+ s = wcslen(p) + 1;
+ array[nr++] = p;
+ p += s;
+ size += s;
+ }
+
+ /* (over-)assess size needed for wchar version of deltaenv */
+ for (delta_size = 0, i = 0; deltaenv[i]; i++)
+ delta_size += strlen(deltaenv[i]) * 2 + 1;
+ ALLOC_ARRAY(wdeltaenv, delta_size);
+
+ /* convert the deltaenv, appending to array */
+ for (i = 0, p = wdeltaenv; deltaenv[i]; i++) {
+ ALLOC_GROW(array, nr + 1, alloc);
+ wlen = xutftowcs(p, deltaenv[i], wdeltaenv + delta_size - p);
+ array[nr++] = p;
+ p += wlen + 1;
+ }
- while (deltaenv && deltaenv[i])
- i++;
+ git_qsort(array, nr, sizeof(*array), wenvcmp);
+ ALLOC_ARRAY(result, size + delta_size);
- /* copy the environment, leaving space for changes */
- ALLOC_ARRAY(tmpenv, size + i);
- memcpy(tmpenv, environ, size * sizeof(char*));
+ for (p = result, i = 0; i < nr; i++) {
+ /* Skip any duplicate keys; last one wins */
+ while (i + 1 < nr && !wenvcmp(array + i, array + i + 1))
+ i++;
- /* merge supplied environment changes into the temporary environment */
- for (i = 0; deltaenv && deltaenv[i]; i++)
- size = do_putenv(tmpenv, deltaenv[i], size, 0);
+ /* Skip "to delete" entry */
+ if (!wcschr(array[i], L'='))
+ continue;
- /* create environment block from temporary environment */
- 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], tmpenv[i], size) + 1;
+ size = wcslen(array[i]) + 1;
+ memcpy(p, array[i], size * sizeof(*p));
+ p += size;
}
- /* add final \0 terminator */
- wenvblk[wenvpos] = 0;
- free(tmpenv);
- return wenvblk;
+ *p = L'\0';
+
+ free(array);
+ free(wdeltaenv);
+ FreeEnvironmentStringsW(wenv);
+ return result;
}
struct pinfo_t {
@@ -1319,87 +1396,83 @@ int mingw_kill(pid_t pid, int sig)
}
/*
- * Compare environment entries by key (i.e. stopping at '=' or '\0').
+ * UTF-8 versions of getenv(), putenv() and unsetenv().
+ * Internally, they use the CRT's stock UNICODE routines
+ * to avoid data loss.
*/
-static int compareenv(const void *v1, const void *v2)
+char *mingw_getenv(const char *name)
{
- const char *e1 = *(const char**)v1;
- const char *e2 = *(const char**)v2;
+#define GETENV_MAX_RETAIN 30
+ static char *values[GETENV_MAX_RETAIN];
+ static int value_counter;
+ int len_key, len_value;
+ wchar_t *w_key;
+ char *value;
+ wchar_t w_value[32768];
- for (;;) {
- int c1 = *e1++;
- int c2 = *e2++;
- c1 = (c1 == '=') ? 0 : tolower(c1);
- c2 = (c2 == '=') ? 0 : tolower(c2);
- if (c1 > c2)
- return 1;
- if (c1 < c2)
- return -1;
- if (c1 == 0)
- return 0;
- }
-}
+ if (!name || !*name)
+ return NULL;
-static int bsearchenv(char **env, const char *name, size_t size)
-{
- unsigned low = 0, high = size;
- while (low < high) {
- unsigned mid = low + ((high - low) >> 1);
- int cmp = compareenv(&env[mid], &name);
- if (cmp < 0)
- low = mid + 1;
- else if (cmp > 0)
- high = mid;
- else
- return mid;
+ len_key = strlen(name) + 1;
+ /* We cannot use xcalloc() here because that uses getenv() itself */
+ w_key = calloc(len_key, sizeof(wchar_t));
+ if (!w_key)
+ die("Out of memory, (tried to allocate %u wchar_t's)", len_key);
+ xutftowcs(w_key, name, len_key);
+ len_value = GetEnvironmentVariableW(w_key, w_value, ARRAY_SIZE(w_value));
+ if (!len_value && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
+ free(w_key);
+ return NULL;
}
- return ~low; /* not found, return 1's complement of insert position */
+ free(w_key);
+
+ len_value = len_value * 3 + 1;
+ /* We cannot use xcalloc() here because that uses getenv() itself */
+ value = calloc(len_value, sizeof(char));
+ if (!value)
+ die("Out of memory, (tried to allocate %u bytes)", len_value);
+ xwcstoutf(value, w_value, len_value);
+
+ /*
+ * We return `value` which is an allocated value and the caller is NOT
+ * expecting to have to free it, so we keep a round-robin array,
+ * invalidating the buffer after GETENV_MAX_RETAIN getenv() calls.
+ */
+ free(values[value_counter]);
+ values[value_counter++] = value;
+ if (value_counter >= ARRAY_SIZE(values))
+ value_counter = 0;
+
+ return value;
}
-/*
- * 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 int do_putenv(char **env, const char *name, int size, int free_old)
+int mingw_putenv(const char *namevalue)
{
- int i = bsearchenv(env, name, size - 1);
+ int size;
+ wchar_t *wide, *equal;
+ BOOL result;
- /* optionally free removed / replaced entry */
- if (i >= 0 && free_old)
- free(env[i]);
+ if (!namevalue || !*namevalue)
+ return 0;
- if (strchr(name, '=')) {
- /* if new value ('key=value') is specified, insert or replace entry */
- if (i < 0) {
- i = ~i;
- memmove(&env[i + 1], &env[i], (size - i) * sizeof(char*));
- size++;
- }
- env[i] = (char*) name;
- } else if (i >= 0) {
- /* otherwise ('key') remove existing entry */
- size--;
- memmove(&env[i], &env[i + 1], (size - i) * sizeof(char*));
+ size = strlen(namevalue) * 2 + 1;
+ wide = calloc(size, sizeof(wchar_t));
+ if (!wide)
+ die("Out of memory, (tried to allocate %u wchar_t's)", size);
+ xutftowcs(wide, namevalue, size);
+ equal = wcschr(wide, L'=');
+ if (!equal)
+ result = SetEnvironmentVariableW(wide, NULL);
+ else {
+ *equal = L'\0';
+ result = SetEnvironmentVariableW(wide, equal + 1);
}
- return size;
-}
+ free(wide);
-char *mingw_getenv(const char *name)
-{
- char *value;
- int pos = bsearchenv(environ, name, environ_size - 1);
- if (pos < 0)
- return NULL;
- value = strchr(environ[pos], '=');
- return value ? &value[1] : NULL;
-}
+ if (!result)
+ errno = err_win_to_posix(GetLastError());
-int mingw_putenv(const char *namevalue)
-{
- ALLOC_GROW(environ, (environ_size + 1) * sizeof(char*), environ_alloc);
- environ_size = do_putenv(environ, namevalue, environ_size, 1);
- return 0;
+ return result ? 0 : -1;
}
/*
@@ -2261,17 +2334,6 @@ void mingw_startup(void)
maxlen = wcslen(wargv[0]);
for (i = 1; i < argc; i++)
maxlen = max(maxlen, wcslen(wargv[i]));
- for (i = 0; wenv[i]; i++)
- maxlen = max(maxlen, wcslen(wenv[i]));
-
- /*
- * nedmalloc can't free CRT memory, allocate resizable environment
- * list. Note that xmalloc / xmemdupz etc. call getenv, so we cannot
- * use it while initializing the environment itself.
- */
- environ_size = i + 1;
- environ_alloc = alloc_nr(environ_size * sizeof(char*));
- environ = malloc_startup(environ_alloc);
/* allocate buffer (wchar_t encodes to max 3 UTF-8 bytes) */
maxlen = 3 * maxlen + 1;
@@ -2280,14 +2342,8 @@ void mingw_startup(void)
/* convert command line arguments and environment to UTF-8 */
for (i = 0; i < argc; i++)
__argv[i] = wcstoutfdup_startup(buffer, wargv[i], maxlen);
- for (i = 0; wenv[i]; i++)
- environ[i] = wcstoutfdup_startup(buffer, wenv[i], maxlen);
- environ[i] = NULL;
free(buffer);
- /* sort environment for O(log n) getenv / putenv */
- qsort(environ, i, sizeof(char*), compareenv);
-
/* fix Windows specific environment settings */
setup_windows_environment();