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Unify some tar functionality across different parts
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Move some of the tar functionality that existed mostly duplicated
in both pg_dump and the walsender basebackup functionality into
port/tar.c instead, so it can be used from both. It will also be
used by pg_basebackup in the future, which would've caused a third
copy of it around.

Zoltan Boszormenyi and Magnus Hagander
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@mhagander
mhagander committed Jan 1, 2013
1 parent a266f7d commit f5d4bdd
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Showing 5 changed files with 154 additions and 228 deletions.
128 changes: 3 additions & 125 deletions src/backend/replication/basebackup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -740,49 +740,13 @@ sendDir(char *path, int basepathlen, bool sizeonly)
*/


/*
* Utility routine to print possibly larger than 32 bit integers in a
* portable fashion. Filled with zeros.
*/
static void
print_val(char *s, uint64 val, unsigned int base, size_t len)
{
int i;

for (i = len; i > 0; i--)
{
int digit = val % base;

s[i - 1] = '0' + digit;
val = val / base;
}
}

/*
* Maximum file size for a tar member: The limit inherent in the
* format is 2^33-1 bytes (nearly 8 GB). But we don't want to exceed
* what we can represent in pgoff_t.
*/
#define MAX_TAR_MEMBER_FILELEN (((int64) 1 << Min(33, sizeof(pgoff_t)*8 - 1)) - 1)

static int
_tarChecksum(char *header)
{
int i,
sum;

/*
* Per POSIX, the checksum is the simple sum of all bytes in the header,
* treating the bytes as unsigned, and treating the checksum field (at
* offset 148) as though it contained 8 spaces.
*/
sum = 8 * ' '; /* presumed value for checksum field */
for (i = 0; i < 512; i++)
if (i < 148 || i >= 156)
sum += 0xFF & header[i];
return sum;
}

/*
* Given the member, write the TAR header & send the file.
*
Expand Down Expand Up @@ -874,95 +838,9 @@ _tarWriteHeader(const char *filename, const char *linktarget,
{
char h[512];

/*
* Note: most of the fields in a tar header are not supposed to be
* null-terminated. We use sprintf, which will write a null after the
* required bytes; that null goes into the first byte of the next field.
* This is okay as long as we fill the fields in order.
*/
memset(h, 0, sizeof(h));

/* Name 100 */
sprintf(&h[0], "%.99s", filename);
if (linktarget != NULL || S_ISDIR(statbuf->st_mode))
{
/*
* We only support symbolic links to directories, and this is
* indicated in the tar format by adding a slash at the end of the
* name, the same as for regular directories.
*/
int flen = strlen(filename);

flen = Min(flen, 99);
h[flen] = '/';
h[flen + 1] = '\0';
}

/* Mode 8 */
sprintf(&h[100], "%07o ", (int) statbuf->st_mode);

/* User ID 8 */
sprintf(&h[108], "%07o ", statbuf->st_uid);

/* Group 8 */
sprintf(&h[116], "%07o ", statbuf->st_gid);

/* File size 12 - 11 digits, 1 space; use print_val for 64 bit support */
if (linktarget != NULL || S_ISDIR(statbuf->st_mode))
/* Symbolic link or directory has size zero */
print_val(&h[124], 0, 8, 11);
else
print_val(&h[124], statbuf->st_size, 8, 11);
sprintf(&h[135], " ");

/* Mod Time 12 */
sprintf(&h[136], "%011o ", (int) statbuf->st_mtime);

/* Checksum 8 cannot be calculated until we've filled all other fields */

if (linktarget != NULL)
{
/* Type - Symbolic link */
sprintf(&h[156], "2");
/* Link Name 100 */
sprintf(&h[157], "%.99s", linktarget);
}
else if (S_ISDIR(statbuf->st_mode))
/* Type - directory */
sprintf(&h[156], "5");
else
/* Type - regular file */
sprintf(&h[156], "0");

/* Magic 6 */
sprintf(&h[257], "ustar");

/* Version 2 */
sprintf(&h[263], "00");

/* User 32 */
/* XXX: Do we need to care about setting correct username? */
sprintf(&h[265], "%.31s", "postgres");

/* Group 32 */
/* XXX: Do we need to care about setting correct group name? */
sprintf(&h[297], "%.31s", "postgres");

/* Major Dev 8 */
sprintf(&h[329], "%07o ", 0);

/* Minor Dev 8 */
sprintf(&h[337], "%07o ", 0);

/* Prefix 155 - not used, leave as nulls */

/*
* We mustn't overwrite the next field while inserting the checksum.
* Fortunately, the checksum can't exceed 6 octal digits, so we just write
* 6 digits, a space, and a null, which is legal per POSIX.
*/
sprintf(&h[148], "%06o ", _tarChecksum(h));
tarCreateHeader(h, filename, linktarget, statbuf->st_size,
statbuf->st_mode, statbuf->st_uid, statbuf->st_gid,
statbuf->st_mtime);

/* Now send the completed header. */
pq_putmessage('d', h, 512);
}
105 changes: 3 additions & 102 deletions src/bin/pg_dump/pg_backup_tar.c
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Original file line number Diff line number Diff line change
Expand Up @@ -115,7 +115,6 @@ static char *tarGets(char *buf, size_t len, TAR_MEMBER *th);
static int tarPrintf(ArchiveHandle *AH, TAR_MEMBER *th, const char *fmt,...) __attribute__((format(PG_PRINTF_ATTRIBUTE, 3, 4)));

static void _tarAddFile(ArchiveHandle *AH, TAR_MEMBER *th);
static int _tarChecksum(char *th);
static TAR_MEMBER *_tarPositionTo(ArchiveHandle *AH, const char *filename);
static size_t tarRead(void *buf, size_t len, TAR_MEMBER *th);
static size_t tarWrite(const void *buf, size_t len, TAR_MEMBER *th);
Expand Down Expand Up @@ -1016,29 +1015,11 @@ tarPrintf(ArchiveHandle *AH, TAR_MEMBER *th, const char *fmt,...)
return cnt;
}

static int
_tarChecksum(char *header)
{
int i,
sum;

/*
* Per POSIX, the checksum is the simple sum of all bytes in the header,
* treating the bytes as unsigned, and treating the checksum field (at
* offset 148) as though it contained 8 spaces.
*/
sum = 8 * ' '; /* presumed value for checksum field */
for (i = 0; i < 512; i++)
if (i < 148 || i >= 156)
sum += 0xFF & header[i];
return sum;
}

bool
isValidTarHeader(char *header)
{
int sum;
int chk = _tarChecksum(header);
int chk = tarChecksum(header);

sscanf(&header[148], "%8o", &sum);

Expand Down Expand Up @@ -1251,7 +1232,7 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
(unsigned long) len);

/* Calc checksum */
chk = _tarChecksum(h);
chk = tarChecksum(h);
sscanf(&h[148], "%8o", &sum);

/*
Expand Down Expand Up @@ -1305,92 +1286,12 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
}


/*
* Utility routine to print possibly larger than 32 bit integers in a
* portable fashion. Filled with zeros.
*/
static void
print_val(char *s, uint64 val, unsigned int base, size_t len)
{
int i;

for (i = len; i > 0; i--)
{
int digit = val % base;

s[i - 1] = '0' + digit;
val = val / base;
}
}


static void
_tarWriteHeader(TAR_MEMBER *th)
{
char h[512];

/*
* Note: most of the fields in a tar header are not supposed to be
* null-terminated. We use sprintf, which will write a null after the
* required bytes; that null goes into the first byte of the next field.
* This is okay as long as we fill the fields in order.
*/
memset(h, 0, sizeof(h));

/* Name 100 */
sprintf(&h[0], "%.99s", th->targetFile);

/* Mode 8 */
sprintf(&h[100], "0000600 ");

/* User ID 8 */
sprintf(&h[108], "0004000 ");

/* Group 8 */
sprintf(&h[116], "0002000 ");

/* File size 12 - 11 digits, 1 space; use print_val for 64 bit support */
print_val(&h[124], th->fileLen, 8, 11);
sprintf(&h[135], " ");

/* Mod Time 12 */
sprintf(&h[136], "%011o ", (int) time(NULL));

/* Checksum 8 cannot be calculated until we've filled all other fields */

/* Type - regular file */
sprintf(&h[156], "0");

/* Link Name 100 (leave as nulls) */

/* Magic 6 */
sprintf(&h[257], "ustar");

/* Version 2 */
sprintf(&h[263], "00");

/* User 32 */
/* XXX: Do we need to care about setting correct username? */
sprintf(&h[265], "%.31s", "postgres");

/* Group 32 */
/* XXX: Do we need to care about setting correct group name? */
sprintf(&h[297], "%.31s", "postgres");

/* Major Dev 8 */
sprintf(&h[329], "%07o ", 0);

/* Minor Dev 8 */
sprintf(&h[337], "%07o ", 0);

/* Prefix 155 - not used, leave as nulls */

/*
* We mustn't overwrite the next field while inserting the checksum.
* Fortunately, the checksum can't exceed 6 octal digits, so we just write
* 6 digits, a space, and a null, which is legal per POSIX.
*/
sprintf(&h[148], "%06o ", _tarChecksum(h));
tarCreateHeader(h, th->targetFile, NULL, th->fileLen, 0600, 04000, 02000, time(NULL));

/* Now write the completed header. */
if (fwrite(h, 1, 512, th->tarFH) != 512)
Expand Down
4 changes: 4 additions & 0 deletions src/include/port.h
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Original file line number Diff line number Diff line change
Expand Up @@ -465,4 +465,8 @@ extern int pg_check_dir(const char *dir);
/* port/pgmkdirp.c */
extern int pg_mkdir_p(char *path, int omode);

/* port/tar.c */
void tarCreateHeader(char *h, const char *filename, const char *linktarget, size_t size, mode_t mode, uid_t uid, gid_t gid, time_t mtime);
int tarChecksum(char *header);

#endif /* PG_PORT_H */
2 changes: 1 addition & 1 deletion src/port/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ LIBS += $(PTHREAD_LIBS)

OBJS = $(LIBOBJS) chklocale.o dirmod.o erand48.o exec.o fls.o inet_net_ntop.o \
noblock.o path.o pgcheckdir.o pg_crc.o pgmkdirp.o pgsleep.o \
pgstrcasecmp.o qsort.o qsort_arg.o sprompt.o thread.o
pgstrcasecmp.o qsort.o qsort_arg.o sprompt.o tar.o thread.o

# foo_srv.o and foo.o are both built from foo.c, but only foo.o has -DFRONTEND
OBJS_SRV = $(OBJS:%.o=%_srv.o)
Expand Down
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