sbase

suckless unix tools
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commit ab267a87ebf9e8819cd604b3daa12ad6c68b71aa
parent fb1595a69c091a6f6a9303b1fab19360b876d114
Author: sin <sin@2f30.org>
Date:   Thu Apr 23 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:
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; }