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If the local file does not exist, or is a regular file, and we're not trying

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to resume a transfer, download the requested document into a temporary file
which we later rename.  This avoids leaving half-completed files around in
case of a crash (it'll still leave a half-completed file, but with a  hope-
fully non-conflicting name), and should reduce the need for human inter-
vention on ports-building machines.

The temporary file name for "foo/bar" is constructed by invoking mkstemps()
with the pattern "foo/.fetch.XXXXXX.bar"

Requested by:	obrien
This commit is contained in:
des 2001-09-08 15:17:15 +00:00
parent 6ac93bff0d
commit 80b788da32
1 changed files with 71 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
usr.bin/fetch/fetch.c
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@ -245,17 +245,20 @@ fetch(char *URL, const char *path)
{
struct url *url;
struct url_stat us;
struct stat sb;
struct stat sb, nsb;
struct xferstat xs;
FILE *f, *of;
size_t size, wr;
off_t count;
char flags[8];
const char *slash;
char *tmppath;
int r;
u_int timeout;
u_char *ptr;
f = of = NULL;
tmppath = NULL;
/* parse URL */
if ((url = fetchParseURL(URL)) == NULL) {
@ -336,12 +339,13 @@ fetch(char *URL, const char *path)
* file was a truncated copy of the remote file; we can drop
* the connection later if we change our minds.
*/
if ((r_flag || m_flag) && !o_stdout && stat(path, &sb) != -1) {
if (r_flag)
url->offset = sb.st_size;
} else {
sb.st_size = -1;
if (!o_stdout && stat(path, &sb) == -1 && errno != ENOENT) {
warnx("%s: stat()", path);
goto failure;
}
if (!o_stdout && r_flag && S_ISREG(sb.st_mode))
url->offset = sb.st_size;
/* start the transfer */
if ((f = fetchXGet(url, &us, flags)) == NULL) {
@ -387,7 +391,7 @@ fetch(char *URL, const char *path)
if (o_stdout) {
/* output to stdout */
of = stdout;
} else if (sb.st_size != -1) {
} else if (r_flag && sb.st_size != -1) {
/* resume mode, local file exists */
if (!F_flag && us.mtime && sb.st_mtime != us.mtime) {
/* no match! have to refetch */
@ -398,13 +402,6 @@ fetch(char *URL, const char *path)
"does not match remote", path);
goto failure_keep;
}
url->offset = 0;
if ((f = fetchXGet(url, &us, flags)) == NULL) {
warnx("%s: %s", path, fetchLastErrString);
goto failure;
}
if (sigint)
goto signal;
} else {
if (us.size == sb.st_size)
/* nothing to do */
@ -416,34 +413,73 @@ fetch(char *URL, const char *path)
(long long)sb.st_size, (long long)us.size);
goto failure;
}
/* we got it, open local file and seek to offset */
/*
* XXX there's a race condition here - the
* file we open is not necessarily the same as
* the one we stat()'ed earlier...
*/
/* we got it, open local file */
if ((of = fopen(path, "a")) == NULL) {
warn("%s: fopen()", path);
goto failure;
}
if (fseek(of, url->offset, SEEK_SET) == -1) {
warn("%s: fseek()", path);
/* check that it didn't move under our feet */
if (fstat(fileno(of), &nsb) == -1) {
/* can't happen! */
warn("%s: fstat()", path);
goto failure;
}
if (nsb.st_dev != sb.st_dev ||
nsb.st_ino != nsb.st_ino ||
nsb.st_size != sb.st_size) {
warnx("%s: file has changed", path);
fclose(of);
of = NULL;
sb = nsb;
}
}
if (m_flag && sb.st_size != -1) {
} else if (m_flag && sb.st_size != -1) {
/* mirror mode, local file exists */
if (sb.st_size == us.size && sb.st_mtime == us.mtime)
goto success;
}
if (!of) {
if (of == NULL) {
/*
* We don't yet have an output file; either this is a
* vanilla run with no special flags, or the local and
* remote files didn't match.
*/
if ((of = fopen(path, "w")) == NULL) {
if (url->offset != 0) {
/*
* We tried to restart a transfer, but for
* some reason gave up - so we have to restart
* from scratch if we want the whole file
*/
url->offset = 0;
if ((f = fetchXGet(url, &us, flags)) == NULL) {
warnx("%s: %s", path, fetchLastErrString);
goto failure;
}
if (sigint)
goto signal;
}
/* construct a temp file name */
if (sb.st_size != -1 && S_ISREG(sb.st_mode)) {
if ((slash = strrchr(path, '/')) == NULL)
slash = path;
else
++slash;
asprintf(&tmppath, "%.*s.fetch.XXXXXX.%s",
slash - path, path, slash);
}
if (tmppath != NULL) {
mkstemps(tmppath, strlen(slash) + 1);
warnx("tmppath: %s", tmppath);
of = fopen(tmppath, "w");
} else {
of = fopen(path, "w");
}
if (of == NULL) {
warn("%s: open()", path);
goto failure;
}
@ -545,11 +581,17 @@ fetch(char *URL, const char *path)
success:
r = 0;
if (tmppath != NULL && rename(tmppath, path) == -1) {
warn("%s: rename()", path);
goto failure_keep;
}
goto done;
failure:
if (of && of != stdout && !R_flag && !r_flag)
if (stat(path, &sb) != -1 && (sb.st_mode & S_IFREG))
unlink(path);
unlink(tmppath ? tmppath : path);
if (R_flag && tmppath != NULL && sb.st_size == -1)
rename(tmppath, path); /* ignore errors here */
failure_keep:
r = -1;
goto done;
@ -560,6 +602,8 @@ fetch(char *URL, const char *path)
fclose(of);
if (url)
fetchFreeURL(url);
if (tmppath != NULL)
free(tmppath);
return r;
}