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gen_init_cpio: write to fd instead of stdout stream

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In preparation for more efficient archiving using copy_file_range(),
switch from writing archive data to stdout to using STDOUT_FILENO and
I/O via write(), dprintf(), etc.
Basic I/O error handling is added to cover cases such as ENOSPC. Partial
writes are treated as errors.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250819032607.28727-2-ddiss@suse.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
This commit is contained in:
David Disseldorp
2025-08-19 13:05:44 +10:00
committed by Nathan Chancellor
parent 75a6b4595d
commit 1400227773
1 changed files with 81 additions and 58 deletions
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139
usr/gen_init_cpio.c
View File

@@ -23,64 +23,71 @@
#define xstr(s) #s
#define str(s) xstr(s)
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define CPIO_HDR_LEN 110
#define padlen(_off, _align) (((_align) - ((_off) & ((_align) - 1))) % (_align))
static char padding[512];
static unsigned int offset;
static unsigned int ino = 721;
static time_t default_mtime;
static bool do_file_mtime;
static bool do_csum = false;
static int outfd = STDOUT_FILENO;
struct file_handler {
const char *type;
int (*handler)(const char *line);
};
static void push_string(const char *name)
static int push_string(const char *name)
{
unsigned int name_len = strlen(name) + 1;
ssize_t len;
len = write(outfd, name, name_len);
if (len != name_len)
return -1;
fputs(name, stdout);
putchar(0);
offset += name_len;
return 0;
}
static void push_pad (void)
static int push_pad(size_t padlen)
{
while (offset & 3) {
putchar(0);
offset++;
}
ssize_t len = 0;
if (!padlen)
return 0;
if (padlen < sizeof(padding))
len = write(outfd, padding, padlen);
if (len != padlen)
return -1;
offset += padlen;
return 0;
}
static void push_rest(const char *name)
static int push_rest(const char *name)
{
unsigned int name_len = strlen(name) + 1;
unsigned int tmp_ofs;
ssize_t len;
len = write(outfd, name, name_len);
if (len != name_len)
return -1;
fputs(name, stdout);
putchar(0);
offset += name_len;
tmp_ofs = name_len + 110;
while (tmp_ofs & 3) {
putchar(0);
offset++;
tmp_ofs++;
}
return push_pad(padlen(name_len + CPIO_HDR_LEN, 4));
}
static void push_hdr(const char *s)
static int cpio_trailer(void)
{
fputs(s, stdout);
offset += 110;
}
static void cpio_trailer(void)
{
char s[256];
const char name[] = "TRAILER!!!";
int len;
sprintf(s, "%s%08X%08X%08lX%08lX%08X%08lX"
len = dprintf(outfd, "%s%08X%08X%08lX%08lX%08X%08lX"
"%08X%08X%08X%08X%08X%08X%08X",
do_csum ? "070702" : "070701", /* magic */
0, /* ino */
@@ -96,23 +103,24 @@ static void cpio_trailer(void)
0, /* rminor */
(unsigned)strlen(name)+1, /* namesize */
0); /* chksum */
push_hdr(s);
push_rest(name);
offset += len;
while (offset % 512) {
putchar(0);
offset++;
}
if (len != CPIO_HDR_LEN ||
push_rest(name) < 0 ||
push_pad(padlen(offset, 512)) < 0)
return -1;
return 0;
}
static int cpio_mkslink(const char *name, const char *target,
unsigned int mode, uid_t uid, gid_t gid)
{
char s[256];
int len;
if (name[0] == '/')
name++;
sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
len = dprintf(outfd, "%s%08X%08X%08lX%08lX%08X%08lX"
"%08X%08X%08X%08X%08X%08X%08X",
do_csum ? "070702" : "070701", /* magic */
ino++, /* ino */
@@ -128,12 +136,17 @@ static int cpio_mkslink(const char *name, const char *target,
0, /* rminor */
(unsigned)strlen(name) + 1,/* namesize */
0); /* chksum */
push_hdr(s);
push_string(name);
push_pad();
push_string(target);
push_pad();
offset += len;
if (len != CPIO_HDR_LEN ||
push_string(name) < 0 ||
push_pad(padlen(offset, 4)) < 0 ||
push_string(target) < 0 ||
push_pad(padlen(offset, 4)) < 0)
return -1;
return 0;
}
static int cpio_mkslink_line(const char *line)
@@ -157,11 +170,11 @@ static int cpio_mkslink_line(const char *line)
static int cpio_mkgeneric(const char *name, unsigned int mode,
uid_t uid, gid_t gid)
{
char s[256];
int len;
if (name[0] == '/')
name++;
sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
len = dprintf(outfd, "%s%08X%08X%08lX%08lX%08X%08lX"
"%08X%08X%08X%08X%08X%08X%08X",
do_csum ? "070702" : "070701", /* magic */
ino++, /* ino */
@@ -177,8 +190,12 @@ static int cpio_mkgeneric(const char *name, unsigned int mode,
0, /* rminor */
(unsigned)strlen(name) + 1,/* namesize */
0); /* chksum */
push_hdr(s);
push_rest(name);
offset += len;
if (len != CPIO_HDR_LEN ||
push_rest(name) < 0)
return -1;
return 0;
}
@@ -246,7 +263,7 @@ static int cpio_mknod(const char *name, unsigned int mode,
uid_t uid, gid_t gid, char dev_type,
unsigned int maj, unsigned int min)
{
char s[256];
int len;
if (dev_type == 'b')
mode |= S_IFBLK;
@@ -255,7 +272,7 @@ static int cpio_mknod(const char *name, unsigned int mode,
if (name[0] == '/')
name++;
sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
len = dprintf(outfd, "%s%08X%08X%08lX%08lX%08X%08lX"
"%08X%08X%08X%08X%08X%08X%08X",
do_csum ? "070702" : "070701", /* magic */
ino++, /* ino */
@@ -271,8 +288,12 @@ static int cpio_mknod(const char *name, unsigned int mode,
min, /* rminor */
(unsigned)strlen(name) + 1,/* namesize */
0); /* chksum */
push_hdr(s);
push_rest(name);
offset += len;
if (len != CPIO_HDR_LEN ||
push_rest(name) < 0)
return -1;
return 0;
}
@@ -324,11 +345,9 @@ static int cpio_mkfile(const char *name, const char *location,
unsigned int mode, uid_t uid, gid_t gid,
unsigned int nlinks)
{
char s[256];
struct stat buf;
unsigned long size;
int file;
int retval;
int file, retval, len;
int rc = -1;
time_t mtime;
int namesize;
@@ -386,7 +405,7 @@ static int cpio_mkfile(const char *name, const char *location,
if (name[0] == '/')
name++;
namesize = strlen(name) + 1;
sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
len = dprintf(outfd, "%s%08X%08X%08lX%08lX%08X%08lX"
"%08lX%08X%08X%08X%08X%08X%08X",
do_csum ? "070702" : "070701", /* magic */
ino, /* ino */
@@ -402,9 +421,12 @@ static int cpio_mkfile(const char *name, const char *location,
0, /* rminor */
namesize, /* namesize */
size ? csum : 0); /* chksum */
push_hdr(s);
push_string(name);
push_pad();
offset += len;
if (len != CPIO_HDR_LEN ||
push_string(name) < 0 ||
push_pad(padlen(offset, 4)) < 0)
goto error;
while (size) {
unsigned char filebuf[65536];
@@ -417,14 +439,15 @@ static int cpio_mkfile(const char *name, const char *location,
goto error;
}
if (fwrite(filebuf, this_read, 1, stdout) != 1) {
if (write(outfd, filebuf, this_read) != this_read) {
fprintf(stderr, "writing filebuf failed\n");
goto error;
}
offset += this_read;
size -= this_read;
}
push_pad();
if (push_pad(padlen(offset, 4)) < 0)
goto error;
name += namesize;
}
@@ -691,7 +714,7 @@ int main (int argc, char *argv[])
}
}
if (ec == 0)
cpio_trailer();
ec = cpio_trailer();
exit(ec);
}