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feat: Add support for hard links

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This commit is contained in:
apio 2023-01-27 22:46:18 +01:00
parent 94324c502e
commit 3772e9e3a6
Signed by: apio
GPG Key ID: B8A7D06E42258954
4 changed files with 25 additions and 5 deletions
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6
docs/API.md
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@ -77,7 +77,9 @@ This enum lists all supported file types:
`MTAR_SYMLINK`: Symbolic links
Other file types supported in tar archives, such as block/character devices, FIFOs, or hard links, are not supported and minitar will throw an error when encountering one of them. This behavior can be controlled by passing `-DMINITAR_IGNORE_UNSUPPORTED_TYPES=ON` to CMake when configuring, which will make minitar silently ignore such entries instead of panicking.
`MTAR_HARDLINK`: Hard links
Other file types supported in tar archives, such as block/character devices or FIFOs, are not supported and minitar will throw an error when encountering one of them. This behavior can be controlled by passing `-DMINITAR_IGNORE_UNSUPPORTED_TYPES=ON` to CMake when configuring, which will make minitar silently ignore such entries instead of panicking.
### minitar_entry_metadata
`struct minitar_entry_metadata`
@ -88,7 +90,7 @@ This structure represents an entry's metadata, with the following fields:
`name`: A string representing the base name of the entry (the last component of its path). (`char[]`)
`link`: A string representing the file being linked to. (Only applies to symlinks) (`char[]`)
`link`: A string representing the file being linked to. (Only applies to symlinks/hard links) (`char[]`)
`mode`: An integer representing the permissions of the entry. (`mode_t`)

12
examples/untar.c
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@ -98,6 +98,18 @@ int main(int argc, char** argv)
printf("symlink %s -> %s\n", entry.metadata.path, entry.metadata.link);
}
else if (entry.metadata.type == MTAR_HARDLINK)
{
int status = link(entry.metadata.link, entry.metadata.path);
if (status != 0)
{
fprintf(stderr, "Failed to create hard link %s: %s\n", entry.metadata.path, strerror(errno));
break;
}
printf("link %s -> %s\n", entry.metadata.path, entry.metadata.link);
}
}
else
break;

3
minitar.h
View File

@ -21,7 +21,8 @@ enum minitar_file_type
{
MTAR_REGULAR,
MTAR_DIRECTORY,
MTAR_SYMLINK
MTAR_SYMLINK,
MTAR_HARDLINK,
};
struct minitar_entry_internal

9
src/util.c
View File

@ -174,6 +174,8 @@ void minitar_parse_metadata_from_tar_header(const struct tar_header* hdr, struct
metadata->uid = (uid_t)minitar_parse_octal(hdr->uid);
metadata->gid = (gid_t)minitar_parse_octal(hdr->gid);
// These two fields aren't null-terminated.
char* sizeptr = minitar_static_dup(hdr->size, 12);
metadata->size = (size_t)minitar_parse_octal(sizeptr);
@ -186,12 +188,13 @@ void minitar_parse_metadata_from_tar_header(const struct tar_header* hdr, struct
{
case '\0':
case '0': metadata->type = MTAR_REGULAR; break;
case '1': minitar_handle_panic("Links to other files within a tar archive are unsupported");
case '1': metadata->type = MTAR_HARDLINK; break;
case '2': metadata->type = MTAR_SYMLINK; break;
case '3': minitar_handle_panic("Character devices are unsupported");
case '4': minitar_handle_panic("Block devices are unsupported");
case '5': metadata->type = MTAR_DIRECTORY; break;
case '6': minitar_handle_panic("FIFOs are unsupported");
// This case should have been previously handled by minitar_validate_header().
default: minitar_handle_panic("Unknown entry type in tar header");
}
@ -228,7 +231,9 @@ uint32_t minitar_checksum_header(const struct tar_header* hdr)
int minitar_validate_header(const struct tar_header* hdr)
{
#ifdef MINITAR_IGNORE_UNSUPPORTED_TYPES
if (hdr->typeflag != '\0' && hdr->typeflag != '0' && hdr->typeflag != '2' && hdr->typeflag != '5') return 0;
if (hdr->typeflag != '\0' && hdr->typeflag != '0' && hdr->typeflag != '1' && hdr->typeflag != '2' &&
hdr->typeflag != '5')
return 0;
#else
if (hdr->typeflag != '\0' && hdr->typeflag != '0' && hdr->typeflag != '1' && hdr->typeflag != '2' &&
hdr->typeflag != '3' && hdr->typeflag != '4' && hdr->typeflag != '5' && hdr->typeflag != '6')