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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
commit | 5e45211a64149b3c659b90ff2de6fa982a5a93ed (patch) | |
tree | 739caf8c461053357daa9f162bef34516c7bf452 /src/port/tar.c | |
parent | Initial commit. (diff) | |
download | postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.tar.xz postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.zip |
Adding upstream version 15.5.upstream/15.5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/port/tar.c')
-rw-r--r-- | src/port/tar.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/src/port/tar.c b/src/port/tar.c new file mode 100644 index 0000000..4afe9f2 --- /dev/null +++ b/src/port/tar.c @@ -0,0 +1,206 @@ +#include "c.h" + +#include <sys/stat.h> + +#include "pgtar.h" + +/* + * Print a numeric field in a tar header. The field starts at *s and is of + * length len; val is the value to be written. + * + * Per POSIX, the way to write a number is in octal with leading zeroes and + * one trailing space (or NUL, but we use space) at the end of the specified + * field width. + * + * However, the given value may not fit in the available space in octal form. + * If that's true, we use the GNU extension of writing \200 followed by the + * number in base-256 form (ie, stored in binary MSB-first). (Note: here we + * support only non-negative numbers, so we don't worry about the GNU rules + * for handling negative numbers.) + */ +void +print_tar_number(char *s, int len, uint64 val) +{ + if (val < (((uint64) 1) << ((len - 1) * 3))) + { + /* Use octal with trailing space */ + s[--len] = ' '; + while (len) + { + s[--len] = (val & 7) + '0'; + val >>= 3; + } + } + else + { + /* Use base-256 with leading \200 */ + s[0] = '\200'; + while (len > 1) + { + s[--len] = (val & 255); + val >>= 8; + } + } +} + + +/* + * Read a numeric field in a tar header. The field starts at *s and is of + * length len. + * + * The POSIX-approved format for a number is octal, ending with a space or + * NUL. However, for values that don't fit, we recognize the GNU extension + * of \200 followed by the number in base-256 form (ie, stored in binary + * MSB-first). (Note: here we support only non-negative numbers, so we don't + * worry about the GNU rules for handling negative numbers.) + */ +uint64 +read_tar_number(const char *s, int len) +{ + uint64 result = 0; + + if (*s == '\200') + { + /* base-256 */ + while (--len) + { + result <<= 8; + result |= (unsigned char) (*++s); + } + } + else + { + /* octal */ + while (len-- && *s >= '0' && *s <= '7') + { + result <<= 3; + result |= (*s - '0'); + s++; + } + } + return result; +} + + +/* + * Calculate the tar checksum for a header. The header is assumed to always + * be 512 bytes, per the tar standard. + */ +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; +} + + +/* + * Fill in the buffer pointed to by h with a tar format header. This buffer + * must always have space for 512 characters, which is a requirement of + * the tar format. + */ +enum tarError +tarCreateHeader(char *h, const char *filename, const char *linktarget, + pgoff_t size, mode_t mode, uid_t uid, gid_t gid, time_t mtime) +{ + if (strlen(filename) > 99) + return TAR_NAME_TOO_LONG; + + if (linktarget && strlen(linktarget) > 99) + return TAR_SYMLINK_TOO_LONG; + + memset(h, 0, 512); /* assume tar header size */ + + /* Name 100 */ + strlcpy(&h[0], filename, 100); + if (linktarget != NULL || S_ISDIR(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 - this doesn't include the file type bits (S_IFMT) */ + print_tar_number(&h[100], 8, (mode & 07777)); + + /* User ID 8 */ + print_tar_number(&h[108], 8, uid); + + /* Group 8 */ + print_tar_number(&h[116], 8, gid); + + /* File size 12 */ + if (linktarget != NULL || S_ISDIR(mode)) + /* Symbolic link or directory has size zero */ + print_tar_number(&h[124], 12, 0); + else + print_tar_number(&h[124], 12, size); + + /* Mod Time 12 */ + print_tar_number(&h[136], 12, mtime); + + /* Checksum 8 cannot be calculated until we've filled all other fields */ + + if (linktarget != NULL) + { + /* Type - Symbolic link */ + h[156] = '2'; + /* Link Name 100 */ + strlcpy(&h[157], linktarget, 100); + } + else if (S_ISDIR(mode)) + { + /* Type - directory */ + h[156] = '5'; + } + else + { + /* Type - regular file */ + h[156] = '0'; + } + + /* Magic 6 */ + strcpy(&h[257], "ustar"); + + /* Version 2 */ + memcpy(&h[263], "00", 2); + + /* User 32 */ + /* XXX: Do we need to care about setting correct username? */ + strlcpy(&h[265], "postgres", 32); + + /* Group 32 */ + /* XXX: Do we need to care about setting correct group name? */ + strlcpy(&h[297], "postgres", 32); + + /* Major Dev 8 */ + print_tar_number(&h[329], 8, 0); + + /* Minor Dev 8 */ + print_tar_number(&h[337], 8, 0); + + /* Prefix 155 - not used, leave as nulls */ + + /* Finally, compute and insert the checksum */ + print_tar_number(&h[148], 8, tarChecksum(h)); + + return TAR_OK; +} |