GitLab

Ben Gamari pushed to branch wip/T130103 at Glasgow Haskell Compiler / GHC

Commits:

a26cf7dd

by Ben Gamari at 2025-06-16T15:35:11-04:00

rts/linker/LoadArchive: Don't rely on file extensions for identification

Previously archive members would be identified via their file extension,
as described in #13103. We now instead use a more principled approach,
relying on the magic number in the member's header.

As well, we refactor treatment of archive format detection to improve
code clarity and error handling.

Closes #13103.

1 changed file:

rts/linker/LoadArchive.c

Changes:

rts/linker/LoadArchive.c

@@ -33,6 +33,7 @@
  #define DEBUG_LOG(...) IF_DEBUG(linker, debugBelch("loadArchive: " __VA_ARGS__))
++
  #if defined(darwin_HOST_OS) || defined(ios_HOST_OS)
  /* Read 4 bytes and convert to host byte order */
  static uint32_t read4Bytes(const char buf[static 4])
@@ -40,7 +41,7 @@ static uint32_t read4Bytes(const char buf[static 4])
      return ntohl(*(uint32_t*)buf);
+ }
 -static bool loadFatArchive(char tmp[static 20], FILE* f, pathchar* path)
 +static bool loadFatArchive(char input[static 20], FILE* f, pathchar* path)
+ {
      uint32_t nfat_arch, nfat_offset, cputype, cpusubtype;
  #if defined(i386_HOST_ARCH)
@@ -58,8 +59,9 @@ static bool loadFatArchive(char tmp[static 20], FILE* f, pathchar* path)
  #error Unknown Darwin architecture
  #endif
 -    nfat_arch = read4Bytes(tmp + 4);
 +    nfat_arch = read4Bytes(input + 4);
      DEBUG_LOG("found a fat archive containing %d architectures\n", nfat_arch);
 +    char tmp[20];
      nfat_offset = 0;
      for (uint32_t i = 0; i < nfat_arch; i++) {
          /* search for the right arch */
@@ -108,7 +110,40 @@ static bool loadFatArchive(char tmp[static 20], FILE* f, pathchar* path)
+ }
  #endif
 -static StgBool readThinArchiveMember(int n, int memberSize, pathchar* path,
 +enum ObjectFileFormat {
 +    NotObject,
 +    PortableExecutable,
 +    ELF,
 +    MachO32,
 +    MachO64,
 +};
++
 +static enum ObjectFileFormat identifyObjectFile_(char* buf, size_t sz)
 +{
 +    if (sz > 2 && ((uint16_t*)buf)[0] == 0x5a4d) {
 +        return PortableExecutable;
 +    }
 +    if (sz > 4 && memcmp(buf, "\x7f" "ELF", 4) == 0) {
 +        return ELF;
 +    }
 +    if (sz > 4 && ((uint32_t*)buf)[0] == 0xfeedface) {
 +        return MachO32;
 +    }
 +    if (sz > 4 && ((uint32_t*)buf)[0] == 0xfeedfacf) {
 +        return MachO64;
 +    }
 +    return NotObject;
 +}
++
 +static enum ObjectFileFormat identifyObjectFile(FILE *f)
 +{
 +    char buf[32];
 +    ssize_t sz = fread(buf, 1, 32, f);
 +    CHECK(fseek(f, -sz, SEEK_CUR) == 0);
 +    return identifyObjectFile_(buf, sz);
 +}
++
 +static bool readThinArchiveMember(int n, int memberSize, pathchar* path,
          char* fileName, char* image)
+ {
      bool has_succeeded = false;
@@ -149,7 +184,7 @@ inner_fail:
      return has_succeeded;
+ }
 -static bool checkFatArchive(char magic[static 20], FILE* f, pathchar* path)
 +static bool checkFatArchive(char magic[static 4], FILE* f, pathchar* path)
+ {
      bool success = false;
  #if defined(darwin_HOST_OS) || defined(ios_HOST_OS)
@@ -241,46 +276,21 @@ lookupGNUArchiveIndex(int gnuFileIndexSize, char **fileName_,
      return true;
+ }
 -HsInt loadArchive_ (pathchar *path)
 -{
 -    char *image = NULL;
 -    HsInt retcode = 0;
 -    int memberSize;
 -    int memberIdx = 0;
 -    FILE *f = NULL;
 -    int n;
 -    size_t thisFileNameSize = (size_t)-1; /* shut up bogus GCC warning */
 -    char *fileName;
 -    size_t fileNameSize;
 -    bool isGnuIndex, isThin, isImportLib;
 -    char *gnuFileIndex;
 -    int gnuFileIndexSize;
 -    int misalignment = 0;
+-
 -    DEBUG_LOG("start\n");
 -    DEBUG_LOG("Loading archive `%" PATH_FMT "'\n", path);
 +enum ArchiveFormat {
 +    StandardArchive,
 +    ThinArchive,
 +    FatArchive,
 +};
 -    /* Check that we haven't already loaded this archive.
 -       Ignore requests to load multiple times */
 -    if (isAlreadyLoaded(path)) {
 -        IF_DEBUG(linker,
 -                 debugBelch("ignoring repeated load of %" PATH_FMT "\n", path));
 -        return 1; /* success */
 +static bool identifyArchiveFormat(FILE *f, pathchar *path, enum ArchiveFormat *out)
 +{
 +    char tmp[8];
 +    size_t n = fread(tmp, 1, 8, f);
 +    if (n != 8) {
 +        errorBelch("loadArchive: Failed reading header from `%" PATH_FMT "'", path); \
 +        return false;
+     }
 -    gnuFileIndex = NULL;
 -    gnuFileIndexSize = 0;
+-
 -    fileNameSize = 32;
 -    fileName = stgMallocBytes(fileNameSize, "loadArchive(fileName)");
+-
 -    isThin = false;
 -    isImportLib = false;
+-
 -    f = pathopen(path, WSTR("rb"));
 -    if (!f)
 -        FAIL("loadObj: can't read `%" PATH_FMT "'", path);
+-
      /* Check if this is an archive by looking for the magic "!<arch>\n"
       * string.  Usually, if this fails, we belch an error and return.  On
       * Darwin however, we may have a fat archive, which contains archives for
@@ -299,12 +309,10 @@ HsInt loadArchive_ (pathchar *path)
       * its magic "!<arch>\n" string and continue processing just as if
       * we had a single architecture archive.
       */
+-
 -    n = fread ( tmp, 1, 8, f );
 -    if (n != 8) {
 -        FAIL("Failed reading header from `%" PATH_FMT "'", path);
 +    if (strncmp(tmp, "!<arch>\n", 8) == 0) {
 +        *out = StandardArchive;
 +        return true;
+     }
 -    if (strncmp(tmp, "!<arch>\n", 8) == 0) {}
      /* Check if this is a thin archive by looking for the magic string "!<thin>\n"
+      *
       * ar thin libraries have the exact same format as normal archives except they
@@ -321,16 +329,59 @@ HsInt loadArchive_ (pathchar *path)
+      *
       */
      else if (strncmp(tmp, "!<thin>\n", 8) == 0) {
 -        isThin = true;
 +        *out = ThinArchive;
 +        return true;
+     }
      else {
          bool success = checkFatArchive(tmp, f, path);
 -        if (!success)
 -            goto fail;
 +        if (!success) {
 +            return false;
 +        }
 +        *out = FatArchive;
 +        return true;
+     }
 +}
++
 +HsInt loadArchive_ (pathchar *path)
 +{
 +    char *image = NULL;
 +    HsInt retcode = 0;
 +    int memberIdx = 0;
 +    FILE *f = NULL;
 +    size_t thisFileNameSize = (size_t) -1; /* shut up bogus GCC warning */
 +    int misalignment = 0;
++
 +    DEBUG_LOG("start\n");
 +    DEBUG_LOG("Loading archive `%" PATH_FMT "'\n", path);
++
 +    /* Check that we haven't already loaded this archive.
 +       Ignore requests to load multiple times */
 +    if (isAlreadyLoaded(path)) {
 +        IF_DEBUG(linker,
 +                 debugBelch("ignoring repeated load of %" PATH_FMT "\n", path));
 +        return 1; /* success */
 +    }
++
 +    char *gnuFileIndex = NULL;
 +    int gnuFileIndexSize = 0;
++
 +    size_t fileNameSize = 32;
 +    char *fileName = stgMallocBytes(fileNameSize, "loadArchive(fileName)");
++
 +    f = pathopen(path, WSTR("rb"));
 +    if (!f)
 +        FAIL("loadObj: can't read `%" PATH_FMT "'", path);
++
 +    enum ArchiveFormat archive_fmt;
 +    if (!identifyArchiveFormat(f, path, &archive_fmt)) {
 +        FAIL("failed to identify archive format of %" PATH_FMT ".", path);
 +    }
 +    bool isThin = archive_fmt == ThinArchive;
++
      DEBUG_LOG("loading archive contents\n");
      while (1) {
 +        size_t n;
          DEBUG_LOG("reading at %ld\n", ftell(f));
          n = fread ( fileName, 1, 16, f );
          if (n != 16) {
@@ -350,6 +401,7 @@ HsInt loadArchive_ (pathchar *path)
+         }
  #endif
 +        char tmp[32];
          n = fread ( tmp, 1, 12, f );
          if (n != 12)
              FAIL("Failed reading mod time from `%" PATH_FMT "'", path);
@@ -368,9 +420,16 @@ HsInt loadArchive_ (pathchar *path)
          tmp[10] = '\0';
          for (n = 0; isdigit(tmp[n]); n++);
          tmp[n] = '\0';
 -        memberSize = atoi(tmp);
 +        size_t memberSize;
 +        {
 +            char *end;
 +            memberSize = strtol(tmp, &end, 10);
 +            if (tmp == end) {
 +                FAIL("Failed to decode member size");
 +            }
 +        }
 -        DEBUG_LOG("size of this archive member is %d\n", memberSize);
 +        DEBUG_LOG("size of this archive member is %zd\n", memberSize);
          n = fread ( tmp, 1, 2, f );
          if (n != 2)
              FAIL("Failed reading magic from `%" PATH_FMT "'", path);
@@ -378,7 +437,7 @@ HsInt loadArchive_ (pathchar *path)
              FAIL("Failed reading magic from `%" PATH_FMT "' at %ld. Got %c%c",
                   path, ftell(f), tmp[0], tmp[1]);
 -        isGnuIndex = false;
 +        bool isGnuIndex = false;
          /* Check for BSD-variant large filenames */
          if (0 == strncmp(fileName, "#1/", 3)) {
              size_t n = 0;
@@ -459,12 +518,7 @@ HsInt loadArchive_ (pathchar *path)
          DEBUG_LOG("Found member file `%s'\n", fileName);
 -        /* TODO: Stop relying on file extensions to determine input formats.
 -                 Instead try to match file headers. See #13103.  */
 -        isObject = (thisFileNameSize >= 2 && strncmp(fileName + thisFileNameSize - 2, ".o"  , 2) == 0)
 -                || (thisFileNameSize >= 3 && strncmp(fileName + thisFileNameSize - 3, ".lo" , 3) == 0)
 -                || (thisFileNameSize >= 4 && strncmp(fileName + thisFileNameSize - 4, ".p_o", 4) == 0)
 -                || (thisFileNameSize >= 4 && strncmp(fileName + thisFileNameSize - 4, ".obj", 4) == 0);
 +        enum ObjectFileFormat object_fmt = identifyObjectFile(f);
  #if defined(OBJFORMAT_PEi386)
          /*
@@ -478,13 +532,15 @@ HsInt loadArchive_ (pathchar *path)
+         *
          * Linker members (e.g. filename / are skipped since they are not needed)
          */
 -        isImportLib = thisFileNameSize >= 4 && strncmp(fileName + thisFileNameSize - 4, ".dll", 4) == 0;
 +        bool isImportLib = thisFileNameSize >= 4 && strncmp(fileName + thisFileNameSize - 4, ".dll", 4) == 0;
 +#else
 +        bool isImportLib = false;
  #endif // windows
          DEBUG_LOG("\tthisFileNameSize = %d\n", (int)thisFileNameSize);
 -        DEBUG_LOG("\tisObject = %d\n", isObject);
 +        DEBUG_LOG("\tisObject = %d\n", object_fmt);
 -        if (isObject) {
 +        if (object_fmt != NotObject) {
              DEBUG_LOG("Member is an object file...loading...\n");
  #if defined(darwin_HOST_OS) || defined(ios_HOST_OS)
@@ -509,7 +565,7 @@ HsInt loadArchive_ (pathchar *path)
+             }
              else
+             {
 -                n = fread ( image, 1, memberSize, f );
 +                size_t n = fread ( image, 1, memberSize, f );
                  if (n != memberSize) {
                      FAIL("error whilst reading `%" PATH_FMT "'", path);
+                 }
@@ -527,9 +583,11 @@ HsInt loadArchive_ (pathchar *path)
              ObjectCode *oc = mkOc(STATIC_OBJECT, path, image, memberSize, false, archiveMemberName,
                                    misalignment);
  #if defined(OBJFORMAT_MACHO)
 +            ASSERT(object_fmt == MachO32 || object_fmt == MachO64);
              ocInit_MachO( oc );
  #endif
  #if defined(OBJFORMAT_ELF)
 +            ASSERT(object_fmt == ELF);
              ocInit_ELF( oc );
  #endif
@@ -574,7 +632,7 @@ while reading filename from `%" PATH_FMT "'", path);
                            "Skipping...\n");
                  n = fseek(f, memberSize, SEEK_CUR);
                  if (n != 0)
 -                    FAIL("error whilst seeking by %d in `%" PATH_FMT "'",
 +                    FAIL("error whilst seeking by %zd in `%" PATH_FMT "'",
                      memberSize, path);
+             }
  #endif
@@ -585,7 +643,7 @@ while reading filename from `%" PATH_FMT "'", path);
              if (!isThin || thisFileNameSize == 0) {
                  n = fseek(f, memberSize, SEEK_CUR);
                  if (n != 0)
 -                    FAIL("error whilst seeking by %d in `%" PATH_FMT "'",
 +                    FAIL("error whilst seeking by %zd in `%" PATH_FMT "'",
                           memberSize, path);
+             }
+         }