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git/strbuf.c
Jeff King 670c359da3 link_alt_odb_entry: handle normalize_path errors
When we add a new alternate to the list, we try to normalize
out any redundant "..", etc. However, we do not look at the
return value of normalize_path_copy(), and will happily
continue with a path that could not be normalized. Worse,
the normalizing process is done in-place, so we are left
with whatever half-finished working state the normalizing
function was in.

Fortunately, this cannot cause us to read past the end of
our buffer, as that working state will always leave the
NUL from the original path in place. And we do tend to
notice problems when we check is_directory() on the path.
But you can see the nonsense that we feed to is_directory
with an entry like:

  this/../../is/../../way/../../too/../../deep/../../to/../../resolve

in your objects/info/alternates, which yields:

  error: object directory
  /to/e/deep/too/way//ects/this/../../is/../../way/../../too/../../deep/../../to/../../resolve
  does not exist; check .git/objects/info/alternates.

We can easily fix this just by checking the return value.
But that makes it hard to generate a good error message,
since we're normalizing in-place and our input value has
been overwritten by cruft.

Instead, let's provide a strbuf helper that does an in-place
normalize, but restores the original contents on error. This
uses a second buffer under the hood, which is slightly less
efficient, but this is not a performance-critical code path.

The strbuf helper can also properly set the "len" parameter
of the strbuf before returning. Just doing:

  normalize_path_copy(buf.buf, buf.buf);

will shorten the string, but leave buf.len at the original
length. That may be confusing to later code which uses the
strbuf.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-10-10 13:52:36 -07:00

892 lines
19 KiB
C

#include "cache.h"
#include "refs.h"
#include "utf8.h"
int starts_with(const char *str, const char *prefix)
{
for (; ; str++, prefix++)
if (!*prefix)
return 1;
else if (*str != *prefix)
return 0;
}
/*
* Used as the default ->buf value, so that people can always assume
* buf is non NULL and ->buf is NUL terminated even for a freshly
* initialized strbuf.
*/
char strbuf_slopbuf[1];
void strbuf_init(struct strbuf *sb, size_t hint)
{
sb->alloc = sb->len = 0;
sb->buf = strbuf_slopbuf;
if (hint)
strbuf_grow(sb, hint);
}
void strbuf_release(struct strbuf *sb)
{
if (sb->alloc) {
free(sb->buf);
strbuf_init(sb, 0);
}
}
char *strbuf_detach(struct strbuf *sb, size_t *sz)
{
char *res;
strbuf_grow(sb, 0);
res = sb->buf;
if (sz)
*sz = sb->len;
strbuf_init(sb, 0);
return res;
}
void strbuf_attach(struct strbuf *sb, void *buf, size_t len, size_t alloc)
{
strbuf_release(sb);
sb->buf = buf;
sb->len = len;
sb->alloc = alloc;
strbuf_grow(sb, 0);
sb->buf[sb->len] = '\0';
}
void strbuf_grow(struct strbuf *sb, size_t extra)
{
int new_buf = !sb->alloc;
if (unsigned_add_overflows(extra, 1) ||
unsigned_add_overflows(sb->len, extra + 1))
die("you want to use way too much memory");
if (new_buf)
sb->buf = NULL;
ALLOC_GROW(sb->buf, sb->len + extra + 1, sb->alloc);
if (new_buf)
sb->buf[0] = '\0';
}
void strbuf_trim(struct strbuf *sb)
{
strbuf_rtrim(sb);
strbuf_ltrim(sb);
}
void strbuf_rtrim(struct strbuf *sb)
{
while (sb->len > 0 && isspace((unsigned char)sb->buf[sb->len - 1]))
sb->len--;
sb->buf[sb->len] = '\0';
}
void strbuf_ltrim(struct strbuf *sb)
{
char *b = sb->buf;
while (sb->len > 0 && isspace(*b)) {
b++;
sb->len--;
}
memmove(sb->buf, b, sb->len);
sb->buf[sb->len] = '\0';
}
int strbuf_reencode(struct strbuf *sb, const char *from, const char *to)
{
char *out;
int len;
if (same_encoding(from, to))
return 0;
out = reencode_string_len(sb->buf, sb->len, to, from, &len);
if (!out)
return -1;
strbuf_attach(sb, out, len, len);
return 0;
}
void strbuf_tolower(struct strbuf *sb)
{
char *p = sb->buf, *end = sb->buf + sb->len;
for (; p < end; p++)
*p = tolower(*p);
}
struct strbuf **strbuf_split_buf(const char *str, size_t slen,
int terminator, int max)
{
struct strbuf **ret = NULL;
size_t nr = 0, alloc = 0;
struct strbuf *t;
while (slen) {
int len = slen;
if (max <= 0 || nr + 1 < max) {
const char *end = memchr(str, terminator, slen);
if (end)
len = end - str + 1;
}
t = xmalloc(sizeof(struct strbuf));
strbuf_init(t, len);
strbuf_add(t, str, len);
ALLOC_GROW(ret, nr + 2, alloc);
ret[nr++] = t;
str += len;
slen -= len;
}
ALLOC_GROW(ret, nr + 1, alloc); /* In case string was empty */
ret[nr] = NULL;
return ret;
}
void strbuf_list_free(struct strbuf **sbs)
{
struct strbuf **s = sbs;
while (*s) {
strbuf_release(*s);
free(*s++);
}
free(sbs);
}
int strbuf_cmp(const struct strbuf *a, const struct strbuf *b)
{
int len = a->len < b->len ? a->len: b->len;
int cmp = memcmp(a->buf, b->buf, len);
if (cmp)
return cmp;
return a->len < b->len ? -1: a->len != b->len;
}
void strbuf_splice(struct strbuf *sb, size_t pos, size_t len,
const void *data, size_t dlen)
{
if (unsigned_add_overflows(pos, len))
die("you want to use way too much memory");
if (pos > sb->len)
die("`pos' is too far after the end of the buffer");
if (pos + len > sb->len)
die("`pos + len' is too far after the end of the buffer");
if (dlen >= len)
strbuf_grow(sb, dlen - len);
memmove(sb->buf + pos + dlen,
sb->buf + pos + len,
sb->len - pos - len);
memcpy(sb->buf + pos, data, dlen);
strbuf_setlen(sb, sb->len + dlen - len);
}
void strbuf_insert(struct strbuf *sb, size_t pos, const void *data, size_t len)
{
strbuf_splice(sb, pos, 0, data, len);
}
void strbuf_remove(struct strbuf *sb, size_t pos, size_t len)
{
strbuf_splice(sb, pos, len, "", 0);
}
void strbuf_add(struct strbuf *sb, const void *data, size_t len)
{
strbuf_grow(sb, len);
memcpy(sb->buf + sb->len, data, len);
strbuf_setlen(sb, sb->len + len);
}
void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2)
{
strbuf_grow(sb, sb2->len);
memcpy(sb->buf + sb->len, sb2->buf, sb2->len);
strbuf_setlen(sb, sb->len + sb2->len);
}
void strbuf_adddup(struct strbuf *sb, size_t pos, size_t len)
{
strbuf_grow(sb, len);
memcpy(sb->buf + sb->len, sb->buf + pos, len);
strbuf_setlen(sb, sb->len + len);
}
void strbuf_addchars(struct strbuf *sb, int c, size_t n)
{
strbuf_grow(sb, n);
memset(sb->buf + sb->len, c, n);
strbuf_setlen(sb, sb->len + n);
}
void strbuf_addf(struct strbuf *sb, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
strbuf_vaddf(sb, fmt, ap);
va_end(ap);
}
static void add_lines(struct strbuf *out,
const char *prefix1,
const char *prefix2,
const char *buf, size_t size)
{
while (size) {
const char *prefix;
const char *next = memchr(buf, '\n', size);
next = next ? (next + 1) : (buf + size);
prefix = ((prefix2 && (buf[0] == '\n' || buf[0] == '\t'))
? prefix2 : prefix1);
strbuf_addstr(out, prefix);
strbuf_add(out, buf, next - buf);
size -= next - buf;
buf = next;
}
strbuf_complete_line(out);
}
void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size)
{
static char prefix1[3];
static char prefix2[2];
if (prefix1[0] != comment_line_char) {
xsnprintf(prefix1, sizeof(prefix1), "%c ", comment_line_char);
xsnprintf(prefix2, sizeof(prefix2), "%c", comment_line_char);
}
add_lines(out, prefix1, prefix2, buf, size);
}
void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...)
{
va_list params;
struct strbuf buf = STRBUF_INIT;
int incomplete_line = sb->len && sb->buf[sb->len - 1] != '\n';
va_start(params, fmt);
strbuf_vaddf(&buf, fmt, params);
va_end(params);
strbuf_add_commented_lines(sb, buf.buf, buf.len);
if (incomplete_line)
sb->buf[--sb->len] = '\0';
strbuf_release(&buf);
}
void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap)
{
int len;
va_list cp;
if (!strbuf_avail(sb))
strbuf_grow(sb, 64);
va_copy(cp, ap);
len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, cp);
va_end(cp);
if (len < 0)
die("BUG: your vsnprintf is broken (returned %d)", len);
if (len > strbuf_avail(sb)) {
strbuf_grow(sb, len);
len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
if (len > strbuf_avail(sb))
die("BUG: your vsnprintf is broken (insatiable)");
}
strbuf_setlen(sb, sb->len + len);
}
void strbuf_expand(struct strbuf *sb, const char *format, expand_fn_t fn,
void *context)
{
for (;;) {
const char *percent;
size_t consumed;
percent = strchrnul(format, '%');
strbuf_add(sb, format, percent - format);
if (!*percent)
break;
format = percent + 1;
if (*format == '%') {
strbuf_addch(sb, '%');
format++;
continue;
}
consumed = fn(sb, format, context);
if (consumed)
format += consumed;
else
strbuf_addch(sb, '%');
}
}
size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder,
void *context)
{
struct strbuf_expand_dict_entry *e = context;
size_t len;
for (; e->placeholder && (len = strlen(e->placeholder)); e++) {
if (!strncmp(placeholder, e->placeholder, len)) {
if (e->value)
strbuf_addstr(sb, e->value);
return len;
}
}
return 0;
}
void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src)
{
int i, len = src->len;
for (i = 0; i < len; i++) {
if (src->buf[i] == '%')
strbuf_addch(dst, '%');
strbuf_addch(dst, src->buf[i]);
}
}
size_t strbuf_fread(struct strbuf *sb, size_t size, FILE *f)
{
size_t res;
size_t oldalloc = sb->alloc;
strbuf_grow(sb, size);
res = fread(sb->buf + sb->len, 1, size, f);
if (res > 0)
strbuf_setlen(sb, sb->len + res);
else if (oldalloc == 0)
strbuf_release(sb);
return res;
}
ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint)
{
size_t oldlen = sb->len;
size_t oldalloc = sb->alloc;
strbuf_grow(sb, hint ? hint : 8192);
for (;;) {
ssize_t want = sb->alloc - sb->len - 1;
ssize_t got = read_in_full(fd, sb->buf + sb->len, want);
if (got < 0) {
if (oldalloc == 0)
strbuf_release(sb);
else
strbuf_setlen(sb, oldlen);
return -1;
}
sb->len += got;
if (got < want)
break;
strbuf_grow(sb, 8192);
}
sb->buf[sb->len] = '\0';
return sb->len - oldlen;
}
ssize_t strbuf_read_once(struct strbuf *sb, int fd, size_t hint)
{
ssize_t cnt;
strbuf_grow(sb, hint ? hint : 8192);
cnt = xread(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
if (cnt > 0)
strbuf_setlen(sb, sb->len + cnt);
return cnt;
}
ssize_t strbuf_write(struct strbuf *sb, FILE *f)
{
return sb->len ? fwrite(sb->buf, 1, sb->len, f) : 0;
}
#define STRBUF_MAXLINK (2*PATH_MAX)
int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint)
{
size_t oldalloc = sb->alloc;
if (hint < 32)
hint = 32;
while (hint < STRBUF_MAXLINK) {
int len;
strbuf_grow(sb, hint);
len = readlink(path, sb->buf, hint);
if (len < 0) {
if (errno != ERANGE)
break;
} else if (len < hint) {
strbuf_setlen(sb, len);
return 0;
}
/* .. the buffer was too small - try again */
hint *= 2;
}
if (oldalloc == 0)
strbuf_release(sb);
return -1;
}
int strbuf_getcwd(struct strbuf *sb)
{
size_t oldalloc = sb->alloc;
size_t guessed_len = 128;
for (;; guessed_len *= 2) {
strbuf_grow(sb, guessed_len);
if (getcwd(sb->buf, sb->alloc)) {
strbuf_setlen(sb, strlen(sb->buf));
return 0;
}
if (errno != ERANGE)
break;
}
if (oldalloc == 0)
strbuf_release(sb);
else
strbuf_reset(sb);
return -1;
}
#ifdef HAVE_GETDELIM
int strbuf_getwholeline(struct strbuf *sb, FILE *fp, int term)
{
ssize_t r;
if (feof(fp))
return EOF;
strbuf_reset(sb);
/* Translate slopbuf to NULL, as we cannot call realloc on it */
if (!sb->alloc)
sb->buf = NULL;
r = getdelim(&sb->buf, &sb->alloc, term, fp);
if (r > 0) {
sb->len = r;
return 0;
}
assert(r == -1);
/*
* Normally we would have called xrealloc, which will try to free
* memory and recover. But we have no way to tell getdelim() to do so.
* Worse, we cannot try to recover ENOMEM ourselves, because we have
* no idea how many bytes were read by getdelim.
*
* Dying here is reasonable. It mirrors what xrealloc would do on
* catastrophic memory failure. We skip the opportunity to free pack
* memory and retry, but that's unlikely to help for a malloc small
* enough to hold a single line of input, anyway.
*/
if (errno == ENOMEM)
die("Out of memory, getdelim failed");
/*
* Restore strbuf invariants; if getdelim left us with a NULL pointer,
* we can just re-init, but otherwise we should make sure that our
* length is empty, and that the result is NUL-terminated.
*/
if (!sb->buf)
strbuf_init(sb, 0);
else
strbuf_reset(sb);
return EOF;
}
#else
int strbuf_getwholeline(struct strbuf *sb, FILE *fp, int term)
{
int ch;
if (feof(fp))
return EOF;
strbuf_reset(sb);
flockfile(fp);
while ((ch = getc_unlocked(fp)) != EOF) {
if (!strbuf_avail(sb))
strbuf_grow(sb, 1);
sb->buf[sb->len++] = ch;
if (ch == term)
break;
}
funlockfile(fp);
if (ch == EOF && sb->len == 0)
return EOF;
sb->buf[sb->len] = '\0';
return 0;
}
#endif
static int strbuf_getdelim(struct strbuf *sb, FILE *fp, int term)
{
if (strbuf_getwholeline(sb, fp, term))
return EOF;
if (sb->buf[sb->len - 1] == term)
strbuf_setlen(sb, sb->len - 1);
return 0;
}
int strbuf_getline(struct strbuf *sb, FILE *fp)
{
if (strbuf_getwholeline(sb, fp, '\n'))
return EOF;
if (sb->buf[sb->len - 1] == '\n') {
strbuf_setlen(sb, sb->len - 1);
if (sb->len && sb->buf[sb->len - 1] == '\r')
strbuf_setlen(sb, sb->len - 1);
}
return 0;
}
int strbuf_getline_lf(struct strbuf *sb, FILE *fp)
{
return strbuf_getdelim(sb, fp, '\n');
}
int strbuf_getline_nul(struct strbuf *sb, FILE *fp)
{
return strbuf_getdelim(sb, fp, '\0');
}
int strbuf_getwholeline_fd(struct strbuf *sb, int fd, int term)
{
strbuf_reset(sb);
while (1) {
char ch;
ssize_t len = xread(fd, &ch, 1);
if (len <= 0)
return EOF;
strbuf_addch(sb, ch);
if (ch == term)
break;
}
return 0;
}
ssize_t strbuf_read_file(struct strbuf *sb, const char *path, size_t hint)
{
int fd;
ssize_t len;
fd = open(path, O_RDONLY);
if (fd < 0)
return -1;
len = strbuf_read(sb, fd, hint);
close(fd);
if (len < 0)
return -1;
return len;
}
void strbuf_add_lines(struct strbuf *out, const char *prefix,
const char *buf, size_t size)
{
add_lines(out, prefix, NULL, buf, size);
}
void strbuf_addstr_xml_quoted(struct strbuf *buf, const char *s)
{
while (*s) {
size_t len = strcspn(s, "\"<>&");
strbuf_add(buf, s, len);
s += len;
switch (*s) {
case '"':
strbuf_addstr(buf, "&quot;");
break;
case '<':
strbuf_addstr(buf, "&lt;");
break;
case '>':
strbuf_addstr(buf, "&gt;");
break;
case '&':
strbuf_addstr(buf, "&amp;");
break;
case 0:
return;
}
s++;
}
}
static int is_rfc3986_reserved(char ch)
{
switch (ch) {
case '!': case '*': case '\'': case '(': case ')': case ';':
case ':': case '@': case '&': case '=': case '+': case '$':
case ',': case '/': case '?': case '#': case '[': case ']':
return 1;
}
return 0;
}
static int is_rfc3986_unreserved(char ch)
{
return isalnum(ch) ||
ch == '-' || ch == '_' || ch == '.' || ch == '~';
}
static void strbuf_add_urlencode(struct strbuf *sb, const char *s, size_t len,
int reserved)
{
strbuf_grow(sb, len);
while (len--) {
char ch = *s++;
if (is_rfc3986_unreserved(ch) ||
(!reserved && is_rfc3986_reserved(ch)))
strbuf_addch(sb, ch);
else
strbuf_addf(sb, "%%%02x", ch);
}
}
void strbuf_addstr_urlencode(struct strbuf *sb, const char *s,
int reserved)
{
strbuf_add_urlencode(sb, s, strlen(s), reserved);
}
void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes)
{
if (bytes > 1 << 30) {
strbuf_addf(buf, "%u.%2.2u GiB",
(int)(bytes >> 30),
(int)(bytes & ((1 << 30) - 1)) / 10737419);
} else if (bytes > 1 << 20) {
int x = bytes + 5243; /* for rounding */
strbuf_addf(buf, "%u.%2.2u MiB",
x >> 20, ((x & ((1 << 20) - 1)) * 100) >> 20);
} else if (bytes > 1 << 10) {
int x = bytes + 5; /* for rounding */
strbuf_addf(buf, "%u.%2.2u KiB",
x >> 10, ((x & ((1 << 10) - 1)) * 100) >> 10);
} else {
strbuf_addf(buf, "%u bytes", (int)bytes);
}
}
void strbuf_add_absolute_path(struct strbuf *sb, const char *path)
{
if (!*path)
die("The empty string is not a valid path");
if (!is_absolute_path(path)) {
struct stat cwd_stat, pwd_stat;
size_t orig_len = sb->len;
char *cwd = xgetcwd();
char *pwd = getenv("PWD");
if (pwd && strcmp(pwd, cwd) &&
!stat(cwd, &cwd_stat) &&
(cwd_stat.st_dev || cwd_stat.st_ino) &&
!stat(pwd, &pwd_stat) &&
pwd_stat.st_dev == cwd_stat.st_dev &&
pwd_stat.st_ino == cwd_stat.st_ino)
strbuf_addstr(sb, pwd);
else
strbuf_addstr(sb, cwd);
if (sb->len > orig_len && !is_dir_sep(sb->buf[sb->len - 1]))
strbuf_addch(sb, '/');
free(cwd);
}
strbuf_addstr(sb, path);
}
int printf_ln(const char *fmt, ...)
{
int ret;
va_list ap;
va_start(ap, fmt);
ret = vprintf(fmt, ap);
va_end(ap);
if (ret < 0 || putchar('\n') == EOF)
return -1;
return ret + 1;
}
int fprintf_ln(FILE *fp, const char *fmt, ...)
{
int ret;
va_list ap;
va_start(ap, fmt);
ret = vfprintf(fp, fmt, ap);
va_end(ap);
if (ret < 0 || putc('\n', fp) == EOF)
return -1;
return ret + 1;
}
char *xstrdup_tolower(const char *string)
{
char *result;
size_t len, i;
len = strlen(string);
result = xmallocz(len);
for (i = 0; i < len; i++)
result[i] = tolower(string[i]);
result[i] = '\0';
return result;
}
char *xstrvfmt(const char *fmt, va_list ap)
{
struct strbuf buf = STRBUF_INIT;
strbuf_vaddf(&buf, fmt, ap);
return strbuf_detach(&buf, NULL);
}
char *xstrfmt(const char *fmt, ...)
{
va_list ap;
char *ret;
va_start(ap, fmt);
ret = xstrvfmt(fmt, ap);
va_end(ap);
return ret;
}
void strbuf_addftime(struct strbuf *sb, const char *fmt, const struct tm *tm)
{
size_t hint = 128;
size_t len;
if (!*fmt)
return;
strbuf_grow(sb, hint);
len = strftime(sb->buf + sb->len, sb->alloc - sb->len, fmt, tm);
if (!len) {
/*
* strftime reports "0" if it could not fit the result in the buffer.
* Unfortunately, it also reports "0" if the requested time string
* takes 0 bytes. So our strategy is to munge the format so that the
* output contains at least one character, and then drop the extra
* character before returning.
*/
struct strbuf munged_fmt = STRBUF_INIT;
strbuf_addf(&munged_fmt, "%s ", fmt);
while (!len) {
hint *= 2;
strbuf_grow(sb, hint);
len = strftime(sb->buf + sb->len, sb->alloc - sb->len,
munged_fmt.buf, tm);
}
strbuf_release(&munged_fmt);
len--; /* drop munged space */
}
strbuf_setlen(sb, sb->len + len);
}
void strbuf_add_unique_abbrev(struct strbuf *sb, const unsigned char *sha1,
int abbrev_len)
{
int r;
strbuf_grow(sb, GIT_SHA1_HEXSZ + 1);
r = find_unique_abbrev_r(sb->buf + sb->len, sha1, abbrev_len);
strbuf_setlen(sb, sb->len + r);
}
/*
* Returns the length of a line, without trailing spaces.
*
* If the line ends with newline, it will be removed too.
*/
static size_t cleanup(char *line, size_t len)
{
while (len) {
unsigned char c = line[len - 1];
if (!isspace(c))
break;
len--;
}
return len;
}
/*
* Remove empty lines from the beginning and end
* and also trailing spaces from every line.
*
* Turn multiple consecutive empty lines between paragraphs
* into just one empty line.
*
* If the input has only empty lines and spaces,
* no output will be produced.
*
* If last line does not have a newline at the end, one is added.
*
* Enable skip_comments to skip every line starting with comment
* character.
*/
void strbuf_stripspace(struct strbuf *sb, int skip_comments)
{
int empties = 0;
size_t i, j, len, newlen;
char *eol;
/* We may have to add a newline. */
strbuf_grow(sb, 1);
for (i = j = 0; i < sb->len; i += len, j += newlen) {
eol = memchr(sb->buf + i, '\n', sb->len - i);
len = eol ? eol - (sb->buf + i) + 1 : sb->len - i;
if (skip_comments && len && sb->buf[i] == comment_line_char) {
newlen = 0;
continue;
}
newlen = cleanup(sb->buf + i, len);
/* Not just an empty line? */
if (newlen) {
if (empties > 0 && j > 0)
sb->buf[j++] = '\n';
empties = 0;
memmove(sb->buf + j, sb->buf + i, newlen);
sb->buf[newlen + j++] = '\n';
} else {
empties++;
}
}
strbuf_setlen(sb, j);
}
int strbuf_normalize_path(struct strbuf *src)
{
struct strbuf dst = STRBUF_INIT;
strbuf_grow(&dst, src->len);
if (normalize_path_copy(dst.buf, src->buf) < 0) {
strbuf_release(&dst);
return -1;
}
/*
* normalize_path does not tell us the new length, so we have to
* compute it by looking for the new NUL it placed
*/
strbuf_setlen(&dst, strlen(dst.buf));
strbuf_swap(src, &dst);
strbuf_release(&dst);
return 0;
}