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/*
* I'm tired of doing "vsnprintf()" etc just to open a
* file, so here's a "return static buffer with printf"
* interface for paths.
*
* It's obviously not thread-safe. Sue me. But it's quite
* useful for doing things like
*
* f = open(mkpath("%s/%s.git", base, name), O_RDONLY);
*
* which is what it's designed for.
*/
#include "cache.h"
#include "strbuf.h"

static char bad_path[] = "/bad-path/";

static char *get_pathname(void)
{
static char pathname_array[4][PATH_MAX];
static int index;
return pathname_array[3 & ++index];
}

static char *cleanup_path(char *path)
{
/* Clean it up */
if (!memcmp(path, "./", 2)) {
path += 2;
while (*path == '/')
path++;
}
return path;
}

char *mksnpath(char *buf, size_t n, const char *fmt, ...)
{
va_list args;
unsigned len;

va_start(args, fmt);
len = vsnprintf(buf, n, fmt, args);
va_end(args);
if (len >= n) {
strlcpy(buf, bad_path, n);
return buf;
}
return cleanup_path(buf);
}

static char *git_vsnpath(char *buf, size_t n, const char *fmt, va_list args)
{
const char *git_dir = get_git_dir();
size_t len;

len = strlen(git_dir);
if (n < len + 1)
goto bad;
memcpy(buf, git_dir, len);
if (len && !is_dir_sep(git_dir[len-1]))
buf[len++] = '/';
len += vsnprintf(buf + len, n - len, fmt, args);
if (len >= n)
goto bad;
return cleanup_path(buf);
bad:
strlcpy(buf, bad_path, n);
return buf;
}

char *git_snpath(char *buf, size_t n, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
(void)git_vsnpath(buf, n, fmt, args);
va_end(args);
return buf;
}

char *git_pathdup(const char *fmt, ...)
{
char path[PATH_MAX];
va_list args;
va_start(args, fmt);
(void)git_vsnpath(path, sizeof(path), fmt, args);
va_end(args);
return xstrdup(path);
}

char *mkpath(const char *fmt, ...)
{
va_list args;
unsigned len;
char *pathname = get_pathname();

va_start(args, fmt);
len = vsnprintf(pathname, PATH_MAX, fmt, args);
va_end(args);
if (len >= PATH_MAX)
return bad_path;
return cleanup_path(pathname);
}

char *git_path(const char *fmt, ...)
{
const char *git_dir = get_git_dir();
char *pathname = get_pathname();
va_list args;
unsigned len;

len = strlen(git_dir);
if (len > PATH_MAX-100)
return bad_path;
memcpy(pathname, git_dir, len);
if (len && git_dir[len-1] != '/')
pathname[len++] = '/';
va_start(args, fmt);
len += vsnprintf(pathname + len, PATH_MAX - len, fmt, args);
va_end(args);
if (len >= PATH_MAX)
return bad_path;
return cleanup_path(pathname);
}


/* git_mkstemp() - create tmp file honoring TMPDIR variable */
int git_mkstemp(char *path, size_t len, const char *template)
{
const char *tmp;
size_t n;

tmp = getenv("TMPDIR");
if (!tmp)
tmp = "/tmp";
n = snprintf(path, len, "%s/%s", tmp, template);
if (len <= n) {
errno = ENAMETOOLONG;
return -1;
}
return mkstemp(path);
}

/* git_mkstemps() - create tmp file with suffix honoring TMPDIR variable. */
int git_mkstemps(char *path, size_t len, const char *template, int suffix_len)
{
const char *tmp;
size_t n;

tmp = getenv("TMPDIR");
if (!tmp)
tmp = "/tmp";
n = snprintf(path, len, "%s/%s", tmp, template);
if (len <= n) {
errno = ENAMETOOLONG;
return -1;
}
return mkstemps(path, suffix_len);
}

int validate_headref(const char *path)
{
struct stat st;
char *buf, buffer[256];
unsigned char sha1[20];
int fd;
ssize_t len;

if (lstat(path, &st) < 0)
return -1;

/* Make sure it is a "refs/.." symlink */
if (S_ISLNK(st.st_mode)) {
len = readlink(path, buffer, sizeof(buffer)-1);
if (len >= 5 && !memcmp("refs/", buffer, 5))
return 0;
return -1;
}

/*
* Anything else, just open it and try to see if it is a symbolic ref.
*/
fd = open(path, O_RDONLY);
if (fd < 0)
return -1;
len = read_in_full(fd, buffer, sizeof(buffer)-1);
close(fd);

/*
* Is it a symbolic ref?
*/
if (len < 4)
return -1;
if (!memcmp("ref:", buffer, 4)) {
buf = buffer + 4;
len -= 4;
while (len && isspace(*buf))
buf++, len--;
if (len >= 5 && !memcmp("refs/", buf, 5))
return 0;
}

/*
* Is this a detached HEAD?
*/
if (!get_sha1_hex(buffer, sha1))
return 0;

return -1;
}

static struct passwd *getpw_str(const char *username, size_t len)
{
struct passwd *pw;
char *username_z = xmalloc(len + 1);
memcpy(username_z, username, len);
username_z[len] = '\0';
pw = getpwnam(username_z);
free(username_z);
return pw;
}

/*
* Return a string with ~ and ~user expanded via getpw*. If buf != NULL,
* then it is a newly allocated string. Returns NULL on getpw failure or
* if path is NULL.
*/
char *expand_user_path(const char *path)
{
struct strbuf user_path = STRBUF_INIT;
const char *first_slash = strchrnul(path, '/');
const char *to_copy = path;

if (path == NULL)
goto return_null;
if (path[0] == '~') {
const char *username = path + 1;
size_t username_len = first_slash - username;
if (username_len == 0) {
const char *home = getenv("HOME");
strbuf_add(&user_path, home, strlen(home));
} else {
struct passwd *pw = getpw_str(username, username_len);
if (!pw)
goto return_null;
strbuf_add(&user_path, pw->pw_dir, strlen(pw->pw_dir));
}
to_copy = first_slash;
}
strbuf_add(&user_path, to_copy, strlen(to_copy));
return strbuf_detach(&user_path, NULL);
return_null:
strbuf_release(&user_path);
return NULL;
}

/*
* First, one directory to try is determined by the following algorithm.
*
* (0) If "strict" is given, the path is used as given and no DWIM is
* done. Otherwise:
* (1) "~/path" to mean path under the running user's home directory;
* (2) "~user/path" to mean path under named user's home directory;
* (3) "relative/path" to mean cwd relative directory; or
* (4) "/absolute/path" to mean absolute directory.
*
* Unless "strict" is given, we try access() for existence of "%s.git/.git",
* "%s/.git", "%s.git", "%s" in this order. The first one that exists is
* what we try.
*
* Second, we try chdir() to that. Upon failure, we return NULL.
*
* Then, we try if the current directory is a valid git repository.
* Upon failure, we return NULL.
*
* If all goes well, we return the directory we used to chdir() (but
* before ~user is expanded), avoiding getcwd() resolving symbolic
* links. User relative paths are also returned as they are given,
* except DWIM suffixing.
*/
char *enter_repo(char *path, int strict)
{
static char used_path[PATH_MAX];
static char validated_path[PATH_MAX];

if (!path)
return NULL;

if (!strict) {
static const char *suffix[] = {
".git/.git", "/.git", ".git", "", NULL,
};
int len = strlen(path);
int i;
while ((1 < len) && (path[len-1] == '/')) {
path[len-1] = 0;
len--;
}
if (PATH_MAX <= len)
return NULL;
if (path[0] == '~') {
char *newpath = expand_user_path(path);
if (!newpath || (PATH_MAX - 10 < strlen(newpath))) {
free(newpath);
return NULL;
}
/*
* Copy back into the static buffer. A pity
* since newpath was not bounded, but other
* branches of the if are limited by PATH_MAX
* anyway.
*/
strcpy(used_path, newpath); free(newpath);
strcpy(validated_path, path);
path = used_path;
}
else if (PATH_MAX - 10 < len)
return NULL;
else {
path = strcpy(used_path, path);
strcpy(validated_path, path);
}
len = strlen(path);
for (i = 0; suffix[i]; i++) {
strcpy(path + len, suffix[i]);
if (!access(path, F_OK)) {
strcat(validated_path, suffix[i]);
break;
}
}
if (!suffix[i] || chdir(path))
return NULL;
path = validated_path;
}
else if (chdir(path))
return NULL;

if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
validate_headref("HEAD") == 0) {
setenv(GIT_DIR_ENVIRONMENT, ".", 1);
check_repository_format();
return path;
}

return NULL;
}

int set_shared_perm(const char *path, int mode)
{
struct stat st;
int tweak, shared, orig_mode;

if (!shared_repository) {
if (mode)
return chmod(path, mode & ~S_IFMT);
return 0;
}
if (!mode) {
if (lstat(path, &st) < 0)
return -1;
mode = st.st_mode;
orig_mode = mode;
} else
orig_mode = 0;
if (shared_repository < 0)
shared = -shared_repository;
else
shared = shared_repository;
tweak = shared;

if (!(mode & S_IWUSR))
tweak &= ~0222;
if (mode & S_IXUSR)
/* Copy read bits to execute bits */
tweak |= (tweak & 0444) >> 2;
if (shared_repository < 0)
mode = (mode & ~0777) | tweak;
else
mode |= tweak;

if (S_ISDIR(mode)) {
/* Copy read bits to execute bits */
mode |= (shared & 0444) >> 2;
mode |= FORCE_DIR_SET_GID;
}

if (((shared_repository < 0
? (orig_mode & (FORCE_DIR_SET_GID | 0777))
: (orig_mode & mode)) != mode) &&
chmod(path, (mode & ~S_IFMT)) < 0)
return -2;
return 0;
}

const char *make_relative_path(const char *abs, const char *base)
{
static char buf[PATH_MAX + 1];
int i = 0, j = 0;

if (!base || !base[0])
return abs;
while (base[i]) {
if (is_dir_sep(base[i])) {
if (!is_dir_sep(abs[j]))
return abs;
while (is_dir_sep(base[i]))
i++;
while (is_dir_sep(abs[j]))
j++;
continue;
} else if (abs[j] != base[i]) {
return abs;
}
i++;
j++;
}
if (
/* "/foo" is a prefix of "/foo" */
abs[j] &&
/* "/foo" is not a prefix of "/foobar" */
!is_dir_sep(base[i-1]) && !is_dir_sep(abs[j])
)
return abs;
while (is_dir_sep(abs[j]))
j++;
if (!abs[j])
strcpy(buf, ".");
else
strcpy(buf, abs + j);
return buf;
}

/*
* It is okay if dst == src, but they should not overlap otherwise.
*
* Performs the following normalizations on src, storing the result in dst:
* - Ensures that components are separated by '/' (Windows only)
* - Squashes sequences of '/'.
* - Removes "." components.
* - Removes ".." components, and the components the precede them.
* Returns failure (non-zero) if a ".." component appears as first path
* component anytime during the normalization. Otherwise, returns success (0).
*
* Note that this function is purely textual. It does not follow symlinks,
* verify the existence of the path, or make any system calls.
*/
int normalize_path_copy(char *dst, const char *src)
{
char *dst0;

if (has_dos_drive_prefix(src)) {
*dst++ = *src++;
*dst++ = *src++;
}
dst0 = dst;

if (is_dir_sep(*src)) {
*dst++ = '/';
while (is_dir_sep(*src))
src++;
}

for (;;) {
char c = *src;

/*
* A path component that begins with . could be
* special:
* (1) "." and ends -- ignore and terminate.
* (2) "./" -- ignore them, eat slash and continue.
* (3) ".." and ends -- strip one and terminate.
* (4) "../" -- strip one, eat slash and continue.
*/
if (c == '.') {
if (!src[1]) {
/* (1) */
src++;
} else if (is_dir_sep(src[1])) {
/* (2) */
src += 2;
while (is_dir_sep(*src))
src++;
continue;
} else if (src[1] == '.') {
if (!src[2]) {
/* (3) */
src += 2;
goto up_one;
} else if (is_dir_sep(src[2])) {
/* (4) */
src += 3;
while (is_dir_sep(*src))
src++;
goto up_one;
}
}
}

/* copy up to the next '/', and eat all '/' */
while ((c = *src++) != '\0' && !is_dir_sep(c))
*dst++ = c;
if (is_dir_sep(c)) {
*dst++ = '/';
while (is_dir_sep(c))
c = *src++;
src--;
} else if (!c)
break;
continue;

up_one:
/*
* dst0..dst is prefix portion, and dst[-1] is '/';
* go up one level.
*/
dst--; /* go to trailing '/' */
if (dst <= dst0)
return -1;
/* Windows: dst[-1] cannot be backslash anymore */
while (dst0 < dst && dst[-1] != '/')
dst--;
}
*dst = '\0';
return 0;
}

/*
* path = Canonical absolute path
* prefix_list = Colon-separated list of absolute paths
*
* Determines, for each path in prefix_list, whether the "prefix" really
* is an ancestor directory of path. Returns the length of the longest
* ancestor directory, excluding any trailing slashes, or -1 if no prefix
* is an ancestor. (Note that this means 0 is returned if prefix_list is
* "/".) "/foo" is not considered an ancestor of "/foobar". Directories
* are not considered to be their own ancestors. path must be in a
* canonical form: empty components, or "." or ".." components are not
* allowed. prefix_list may be null, which is like "".
*/
int longest_ancestor_length(const char *path, const char *prefix_list)
{
char buf[PATH_MAX+1];
const char *ceil, *colon;
int len, max_len = -1;

if (prefix_list == NULL || !strcmp(path, "/"))
return -1;

for (colon = ceil = prefix_list; *colon; ceil = colon+1) {
for (colon = ceil; *colon && *colon != PATH_SEP; colon++);
len = colon - ceil;
if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
continue;
strlcpy(buf, ceil, len+1);
if (normalize_path_copy(buf, buf) < 0)
continue;
len = strlen(buf);
if (len > 0 && buf[len-1] == '/')
buf[--len] = '\0';

if (!strncmp(path, buf, len) &&
path[len] == '/' &&
len > max_len) {
max_len = len;
}
}

return max_len;
}

/* strip arbitrary amount of directory separators at end of path */
static inline int chomp_trailing_dir_sep(const char *path, int len)
{
while (len && is_dir_sep(path[len - 1]))
len--;
return len;
}

/*
* If path ends with suffix (complete path components), returns the
* part before suffix (sans trailing directory separators).
* Otherwise returns NULL.
*/
char *strip_path_suffix(const char *path, const char *suffix)
{
int path_len = strlen(path), suffix_len = strlen(suffix);

while (suffix_len) {
if (!path_len)
return NULL;

if (is_dir_sep(path[path_len - 1])) {
if (!is_dir_sep(suffix[suffix_len - 1]))
return NULL;
path_len = chomp_trailing_dir_sep(path, path_len);
suffix_len = chomp_trailing_dir_sep(suffix, suffix_len);
}
else if (path[--path_len] != suffix[--suffix_len])
return NULL;
}

if (path_len && !is_dir_sep(path[path_len - 1]))
return NULL;
return xstrndup(path, chomp_trailing_dir_sep(path, path_len));
}

int daemon_avoid_alias(const char *p)
{
int sl, ndot;

/*
* This resurrects the belts and suspenders paranoia check by HPA
* done in <435560F7.4080006@zytor.com> thread, now enter_repo()
* does not do getcwd() based path canonicalizations.
*
* sl becomes true immediately after seeing '/' and continues to
* be true as long as dots continue after that without intervening
* non-dot character.
*/
if (!p || (*p != '/' && *p != '~'))
return -1;
sl = 1; ndot = 0;
p++;

while (1) {
char ch = *p++;
if (sl) {
if (ch == '.')
ndot++;
else if (ch == '/') {
if (ndot < 3)
/* reject //, /./ and /../ */
return -1;
ndot = 0;
}
else if (ch == 0) {
if (0 < ndot && ndot < 3)
/* reject /.$ and /..$ */
return -1;
return 0;
}
else
sl = ndot = 0;
}
else if (ch == 0)
return 0;
else if (ch == '/') {
sl = 1;
ndot = 0;
}
}
}
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