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[PATCH] usr/gen_init_cpio.c: support for hard links
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Extend usr/gen_init_cpio.c "file" entry, adding support for hard links.

Previous format:
file <name> <location> <mode> <uid> <gid>

New format:
file <name> <location> <mode> <uid> <gid> [<hard links>]

The hard links specification is optional, keeping the previous
behaviour.

All hard links are defined sequentially in the resulting cpio and the
file data is present only in the last link. This is the behaviour of
GNU's cpio and is supported by the kernel initramfs extractor.

Signed-off-by: Luciano Rocha <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Luciano Rocha authored and Linus Torvalds committed Feb 11, 2007
1 parent 67d3822 commit 24fa509
Showing 1 changed file with 86 additions and 36 deletions.
122 changes: 86 additions & 36 deletions usr/gen_init_cpio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
* Original work by Jeff Garzik
*
* External file lists, symlink, pipe and fifo support by Thayne Harbaugh
* Hard link support by Luciano Rocha
*/

#define xstr(s) #s
Expand Down Expand Up @@ -286,16 +287,19 @@ static int cpio_mknod_line(const char *line)
return rc;
}

/* Not marked static to keep the compiler quiet, as no one uses this yet... */
static int cpio_mkfile(const char *name, const char *location,
unsigned int mode, uid_t uid, gid_t gid)
unsigned int mode, uid_t uid, gid_t gid,
unsigned int nlinks)
{
char s[256];
char *filebuf = NULL;
struct stat buf;
long size;
int file = -1;
int retval;
int rc = -1;
int namesize;
int i;

mode |= S_IFREG;

Expand Down Expand Up @@ -323,29 +327,41 @@ static int cpio_mkfile(const char *name, const char *location,
goto error;
}

sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
"%08X%08X%08X%08X%08X%08X%08X",
"070701", /* magic */
ino++, /* ino */
mode, /* mode */
(long) uid, /* uid */
(long) gid, /* gid */
1, /* nlink */
(long) buf.st_mtime, /* mtime */
(int) buf.st_size, /* filesize */
3, /* major */
1, /* minor */
0, /* rmajor */
0, /* rminor */
(unsigned)strlen(name) + 1,/* namesize */
0); /* chksum */
push_hdr(s);
push_string(name);
push_pad();
size = 0;
for (i = 1; i <= nlinks; i++) {
/* data goes on last link */
if (i == nlinks) size = buf.st_size;

namesize = strlen(name) + 1;
sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
"%08lX%08X%08X%08X%08X%08X%08X",
"070701", /* magic */
ino, /* ino */
mode, /* mode */
(long) uid, /* uid */
(long) gid, /* gid */
nlinks, /* nlink */
(long) buf.st_mtime, /* mtime */
size, /* filesize */
3, /* major */
1, /* minor */
0, /* rmajor */
0, /* rminor */
namesize, /* namesize */
0); /* chksum */
push_hdr(s);
push_string(name);
push_pad();

if (size) {
fwrite(filebuf, size, 1, stdout);
offset += size;
push_pad();
}

fwrite(filebuf, buf.st_size, 1, stdout);
offset += buf.st_size;
push_pad();
name += namesize;
}
ino++;
rc = 0;

error:
Expand All @@ -357,18 +373,51 @@ static int cpio_mkfile(const char *name, const char *location,
static int cpio_mkfile_line(const char *line)
{
char name[PATH_MAX + 1];
char *dname = NULL; /* malloc'ed buffer for hard links */
char location[PATH_MAX + 1];
unsigned int mode;
int uid;
int gid;
int nlinks = 1;
int end = 0, dname_len = 0;
int rc = -1;

if (5 != sscanf(line, "%" str(PATH_MAX) "s %" str(PATH_MAX) "s %o %d %d", name, location, &mode, &uid, &gid)) {
if (5 > sscanf(line, "%" str(PATH_MAX) "s %" str(PATH_MAX)
"s %o %d %d %n",
name, location, &mode, &uid, &gid, &end)) {
fprintf(stderr, "Unrecognized file format '%s'", line);
goto fail;
}
rc = cpio_mkfile(name, location, mode, uid, gid);
if (end && isgraph(line[end])) {
int len;
int nend;

dname = malloc(strlen(line));
if (!dname) {
fprintf (stderr, "out of memory (%d)\n", dname_len);
goto fail;
}

dname_len = strlen(name) + 1;
memcpy(dname, name, dname_len);

do {
nend = 0;
if (sscanf(line + end, "%" str(PATH_MAX) "s %n",
name, &nend) < 1)
break;
len = strlen(name) + 1;
memcpy(dname + dname_len, name, len);
dname_len += len;
nlinks++;
end += nend;
} while (isgraph(line[end]));
} else {
dname = name;
}
rc = cpio_mkfile(dname, location, mode, uid, gid, nlinks);
fail:
if (dname_len) free(dname);
return rc;
}

Expand All @@ -381,22 +430,23 @@ void usage(const char *prog)
"describe the files to be included in the initramfs archive:\n"
"\n"
"# a comment\n"
"file <name> <location> <mode> <uid> <gid>\n"
"file <name> <location> <mode> <uid> <gid> [<hard links>]\n"
"dir <name> <mode> <uid> <gid>\n"
"nod <name> <mode> <uid> <gid> <dev_type> <maj> <min>\n"
"slink <name> <target> <mode> <uid> <gid>\n"
"pipe <name> <mode> <uid> <gid>\n"
"sock <name> <mode> <uid> <gid>\n"
"\n"
"<name> name of the file/dir/nod/etc in the archive\n"
"<location> location of the file in the current filesystem\n"
"<target> link target\n"
"<mode> mode/permissions of the file\n"
"<uid> user id (0=root)\n"
"<gid> group id (0=root)\n"
"<dev_type> device type (b=block, c=character)\n"
"<maj> major number of nod\n"
"<min> minor number of nod\n"
"<name> name of the file/dir/nod/etc in the archive\n"
"<location> location of the file in the current filesystem\n"
"<target> link target\n"
"<mode> mode/permissions of the file\n"
"<uid> user id (0=root)\n"
"<gid> group id (0=root)\n"
"<dev_type> device type (b=block, c=character)\n"
"<maj> major number of nod\n"
"<min> minor number of nod\n"
"<hard links> space separated list of other links to file\n"
"\n"
"example:\n"
"# A simple initramfs\n"
Expand Down

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