commit ab267a87ebf9e8819cd604b3daa12ad6c68b71aa
parent fb1595a69c091a6f6a9303b1fab19360b876d114
Author: sin <sin@2f30.org>
Date: Thu, 23 Apr 2015 15:20:10 +0100
tar: Use raw I/O instead of standard file streams
As part of refactoring tar to add support for compression through
gzip/bzip2, it makes sense to avoid intermixing file stream I/O with
raw I/O.
Diffstat:
| M | tar.c | | | 124 | +++++++++++++++++++++++++++++++++++++++++++++---------------------------------- |
1 file changed, 70 insertions(+), 54 deletions(-)
diff --git a/tar.c b/tar.c
@@ -3,6 +3,7 @@
#include <sys/time.h>
#include <errno.h>
+#include <fcntl.h>
#include <grp.h>
#include <libgen.h>
#include <pwd.h>
@@ -47,8 +48,7 @@ enum Type {
BLOCKDEV = '4', DIRECTORY = '5', FIFO = '6'
};
-static FILE *tarfile;
-static char *tarfilename;
+static int tarfd;
static ino_t tarinode;
static dev_t tardev;
@@ -59,6 +59,7 @@ static struct ent {
char *name;
time_t mtime;
} *ents;
+
static size_t entlen;
static void
@@ -80,8 +81,8 @@ popent(void)
return NULL;
}
-static FILE *
-decomp(FILE *fp)
+static int
+decomp(int fd)
{
int fds[2];
char *tool;
@@ -93,7 +94,7 @@ decomp(FILE *fp)
case -1:
eprintf("fork:");
case 0:
- dup2(fileno(fp), 0);
+ dup2(fd, 0);
dup2(fds[1], 1);
close(fds[0]);
close(fds[1]);
@@ -104,8 +105,32 @@ decomp(FILE *fp)
_exit(1);
}
close(fds[1]);
+ return fds[0];
+}
+
+static ssize_t
+eread(int fd, void *buf, size_t n)
+{
+ ssize_t r;
+
+again:
+ r = read(fd, buf, n);
+ if (r < 0) {
+ if (errno == EINTR)
+ goto again;
+ eprintf("read:");
+ }
+ return r;
+}
- return fdopen(fds[0], "r");
+static ssize_t
+ewrite(int fd, const void *buf, size_t n)
+{
+ ssize_t r;
+
+ if ((r = write(fd, buf, n)) != n)
+ eprintf("write:");
+ return r;
}
static void
@@ -118,14 +143,14 @@ putoctal(char *dst, unsigned num, int size)
static int
archive(const char *path)
{
- FILE *f = NULL;
+ unsigned char b[BLKSIZ];
struct group *gr;
struct header *h;
struct passwd *pw;
struct stat st;
size_t chksum, x;
ssize_t l, r;
- unsigned char b[BLKSIZ];
+ int fd = -1;
if (lstat(path, &st) < 0) {
weprintf("lstat %s:", path);
@@ -154,7 +179,9 @@ archive(const char *path)
if (S_ISREG(st.st_mode)) {
h->type = REG;
putoctal(h->size, (unsigned)st.st_size, sizeof(h->size));
- f = fopen(path, "r");
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ eprintf("open %s:", path);
} else if (S_ISDIR(st.st_mode)) {
h->type = DIRECTORY;
} else if (S_ISLNK(st.st_mode)) {
@@ -174,18 +201,15 @@ archive(const char *path)
for (x = 0, chksum = 0; x < sizeof(*h); x++)
chksum += b[x];
putoctal(h->chksum, chksum, sizeof(h->chksum));
+ ewrite(tarfd, b, BLKSIZ);
- if (fwrite(b, BLKSIZ, 1, tarfile) != 1)
- eprintf("fwrite:");
-
- if (f) {
- while ((l = fread(b, 1, BLKSIZ, f)) > 0) {
+ if (fd != -1) {
+ while ((l = eread(fd, b, BLKSIZ)) > 0) {
if (l < BLKSIZ)
memset(b + l, 0, BLKSIZ - l);
- if (fwrite(b, BLKSIZ, 1, tarfile) != 1)
- eprintf("fwrite:");
+ ewrite(tarfd, b, BLKSIZ);
}
- efshut(f, path);
+ close(fd);
}
return 0;
@@ -194,10 +218,10 @@ archive(const char *path)
static int
unarchive(char *fname, ssize_t l, char b[BLKSIZ])
{
- FILE *f = NULL;
- struct header *h = (struct header *)b;
- long mode, major, minor, type, mtime, uid, gid;
char lname[101], *tmp, *p;
+ long mode, major, minor, type, mtime, uid, gid;
+ struct header *h = (struct header *)b;
+ int fd = -1;
if (!mflag && ((mtime = strtol(h->mtime, &p, 8)) < 0 || *p != '\0'))
eprintf("strtol %s: invalid number\n", h->mtime);
@@ -213,10 +237,11 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
case AREG:
if ((mode = strtol(h->mode, &p, 8)) < 0 || *p != '\0')
eprintf("strtol %s: invalid number\n", h->mode);
- if (!(f = fopen(fname, "w")))
- eprintf("fopen %s:", fname);
- if (chmod(fname, mode) < 0)
- eprintf("chmod %s:", fname);
+ fd = open(fname, O_WRONLY | O_TRUNC | O_CREAT, 0644);
+ if (fd < 0)
+ eprintf("open %s:", fname);
+ if (fchmod(fd, mode) < 0)
+ eprintf("fchmod %s:", fname);
break;
case HARDLINK:
case SYMLINK:
@@ -262,14 +287,12 @@ unarchive(char *fname, ssize_t l, char b[BLKSIZ])
if (!getuid() && chown(fname, uid, gid))
weprintf("chown %s:", fname);
- for (; l > 0; l -= BLKSIZ) {
- if (fread(b, BLKSIZ, 1, tarfile) != 1)
- eprintf("fread %s:", tarfilename);
- if (f && fwrite(b, MIN(l, BLKSIZ), 1, f) != 1)
- eprintf("fwrite %s:", fname);
+ if (fd != -1) {
+ for (; l > 0; l -= BLKSIZ)
+ if (eread(tarfd, b, BLKSIZ) > 0)
+ ewrite(fd, b, MIN(l, BLKSIZ));
+ close(fd);
}
- if (f)
- fshut(f, fname);
pushent(fname, mtime);
return 0;
@@ -281,8 +304,8 @@ skipblk(ssize_t l)
char b[BLKSIZ];
for (; l > 0; l -= BLKSIZ)
- if (fread(b, BLKSIZ, 1, tarfile) != 1)
- eprintf("fread %s:", tarfilename);
+ if (!eread(tarfd, b, BLKSIZ))
+ break;
}
static int
@@ -339,7 +362,7 @@ xt(int argc, char *argv[], int (*fn)(char *, ssize_t, char[BLKSIZ]))
long size;
int i, n;
- while (fread(b, BLKSIZ, 1, tarfile) == 1 && *h->name) {
+ while (eread(tarfd, b, BLKSIZ) > 0 && h->name[0]) {
sanitize(h), n = 0;
/* small dance around non-null terminated fields */
@@ -371,8 +394,6 @@ xt(int argc, char *argv[], int (*fn)(char *, ssize_t, char[BLKSIZ]))
fn(fname, size, b);
}
- if (ferror(tarfile))
- eprintf("fread %s:", tarfilename);
if (!mflag) {
while ((ent = popent())) {
@@ -397,11 +418,11 @@ usage(void)
int
main(int argc, char *argv[])
{
- FILE *fp;
struct recursor r = { .fn = c, .hist = NULL, .depth = 0, .maxdepth = 0,
.follow = 'P', .flags = DIRFIRST };
struct stat st;
char *file = NULL, *dir = ".", mode = '\0';
+ int fd;
ARGBEGIN {
case 'x':
@@ -437,19 +458,17 @@ main(int argc, char *argv[])
switch (mode) {
case 'c':
+ tarfd = 1;
if (file) {
- if (!(fp = fopen(file, "w")))
- eprintf("fopen %s:", file);
+ tarfd = open(file, O_WRONLY | O_TRUNC | O_CREAT, 0644);
+ if (tarfd < 0)
+ eprintf("open %s:", file);
if (lstat(file, &st) < 0)
eprintf("lstat %s:", file);
tarinode = st.st_ino;
tardev = st.st_dev;
- tarfile = fp;
- tarfilename = file;
- } else {
- tarfile = stdout;
- tarfilename = "<stdout>";
}
+
if (chdir(dir) < 0)
eprintf("chdir %s:", dir);
for (; *argv; argc--, argv++)
@@ -457,22 +476,19 @@ main(int argc, char *argv[])
break;
case 't':
case 'x':
+ tarfd = 0;
if (file) {
- if (!(fp = fopen(file, "r")))
- eprintf("fopen %s:", file);
- } else {
- fp = stdin;
+ tarfd = open(file, O_RDONLY);
+ if (tarfd < 0)
+ eprintf("open %s:", file);
}
- tarfilename = file;
-
switch (filtermode) {
case 'j':
case 'z':
- tarfile = decomp(fp);
- break;
- default:
- tarfile = fp;
+ fd = tarfd;
+ tarfd = decomp(tarfd);
+ close(fd);
break;
}
