diff options
Diffstat (limited to 'libs/utils/BackupHelpers.cpp')
| -rw-r--r-- | libs/utils/BackupHelpers.cpp | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/libs/utils/BackupHelpers.cpp b/libs/utils/BackupHelpers.cpp index cfb013e..e15875f 100644 --- a/libs/utils/BackupHelpers.cpp +++ b/libs/utils/BackupHelpers.cpp @@ -468,6 +468,19 @@ static void calc_tar_checksum(char* buf) { sprintf(buf + 148, "%06o", sum); // the trailing space is already in place } +// Returns number of bytes written +static int write_pax_header_entry(char* buf, const char* key, const char* value) { + // start with the size of "1 key=value\n" + int len = strlen(key) + strlen(value) + 4; + if (len > 9) len++; + if (len > 99) len++; + if (len > 999) len++; + // since PATH_MAX is 4096 we don't expect to have to generate any single + // header entry longer than 9999 characters + + return sprintf(buf, "%d %s=%s\n", len, key, value); +} + int write_tarfile(const String8& packageName, const String8& domain, const String8& rootpath, const String8& filepath, BackupDataWriter* writer) { @@ -525,8 +538,7 @@ int write_tarfile(const String8& packageName, const String8& domain, } // Good to go -- first construct the standard tar header at the start of the buffer - memset(buf, 0, 512); // tar header is 512 bytes - memset(paxHeader, 0, 512); + memset(buf, 0, BUFSIZE); // Magic fields for the ustar file format strcat(buf + 257, "ustar"); @@ -602,24 +614,20 @@ int write_tarfile(const String8& packageName, const String8& domain, // If we're using a pax extended header, build & write that here; lengths are // already preflighted if (needExtended) { + char sizeStr[32]; // big enough for a 64-bit unsigned value in decimal + char* p = paxData; + // construct the pax extended header data block memset(paxData, 0, BUFSIZE - (paxData - buf)); - char* p = paxData; int len; // size header -- calc len in digits by actually rendering the number // to a string - brute force but simple - len = sprintf(p, "%lld", s.st_size) + 8; // 8 for "1 size=" and final LF - if (len >= 10) len++; - - memset(p, 0, 512); - p += sprintf(p, "%d size=%lld\n", len, s.st_size); + snprintf(sizeStr, sizeof(sizeStr), "%lld", s.st_size); + p += write_pax_header_entry(p, "size", sizeStr); // fullname was generated above with the ustar paths - len = fullname.length() + 8; // 8 for "1 path=" and final LF - if (len >= 10) len++; - if (len >= 100) len++; - p += sprintf(p, "%d path=%s\n", len, fullname.string()); + p += write_pax_header_entry(p, "path", fullname.string()); // Now we know how big the pax data is int paxLen = p - paxData; |