Unverified Commit 14002277 authored by David Disseldorp's avatar David Disseldorp Committed by Nathan Chancellor
Browse files

gen_init_cpio: write to fd instead of stdout stream 



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: default avatarDavid Disseldorp <ddiss@suse.de>
Reviewed-by: default avatarNicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250819032607.28727-2-ddiss@suse.de


Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
parent 75a6b459

usr/gen_init_cpio.c

+81 −58
Original line number Diff line number Diff line
@@ -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);

}