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Not all 0-sized reads are errors

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If you requested 0 bytes, the kernel gives you 0 bytes back
This commit is contained in:
apio 2022-11-06 14:14:06 +01:00
parent fd32be351e
commit 28085731f1
1 changed files with 19 additions and 7 deletions
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26
src/util.c
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@ -66,6 +66,9 @@ void minitar_parse_tar_header(struct tar_header* hdr, struct minitar_entry_metad
int minitar_validate_header(struct tar_header* hdr) int minitar_validate_header(struct tar_header* hdr)
{ {
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')
return 0;
return !strncmp(hdr->magic, "ustar", 5); return !strncmp(hdr->magic, "ustar", 5);
} }
@ -73,6 +76,7 @@ int minitar_read_header(struct minitar* mp, struct tar_header* hdr)
{ {
size_t rc = fread(hdr, 1, sizeof *hdr, mp->stream); size_t rc = fread(hdr, 1, sizeof *hdr, mp->stream);
if (rc == 0 && feof(mp->stream)) return 0; if (rc == 0 && feof(mp->stream)) return 0;
if (rc == 0 && ferror(mp->stream)) minitar_panic("Error while reading file header from tar archive");
if (rc < sizeof *hdr) minitar_panic("Valid tar files should be split in 512-byte blocks"); if (rc < sizeof *hdr) minitar_panic("Valid tar files should be split in 512-byte blocks");
return 1; return 1;
} }
@ -93,14 +97,22 @@ char* minitar_read_file(struct minitar_entry_metadata* metadata, struct minitar*
size_t nread = fread(buf, 1, metadata->size, mp->stream); size_t nread = fread(buf, 1, metadata->size, mp->stream);
if (!nread) if (!nread)
{ {
free(buf); if (feof(mp->stream))
if (feof(mp->stream)) return NULL; {
if (ferror(mp->stream)) minitar_panic("Error while reading file data from tar archive"); free(buf);
__builtin_unreachable(); return NULL;
}
if (ferror(mp->stream))
{
free(buf);
minitar_panic("Error while reading file data from tar archive");
}
}
else
{
long rem = 512 - (nread % 512);
fseek(mp->stream, rem, SEEK_CUR); // move the file offset over to the start of the next block
} }
long rem = 512 - (nread % 512);
fseek(mp->stream, rem, SEEK_CUR); // move the file offset over to the start of the next block
buf[nread] = 0; buf[nread] = 0;