Make Windows symbol-prefixing work.
This teaches read_symbols.go to use debug/pe, and fixes miscellaneous
issues with NASM. It also reveals a problem with this strategy of
getting symbols out at the linker level: inline functions. I'm thinking
a better long-term mechanism may be to parse our header files.
Change-Id: I11b008543a7a97db3db9d4062ee4ddb910d174b7
Reviewed-on: https://boringssl-review.googlesource.com/c/33349
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/util/make_prefix_headers.go b/util/make_prefix_headers.go
index a5e5441..b536f14 100644
--- a/util/make_prefix_headers.go
+++ b/util/make_prefix_headers.go
@@ -172,16 +172,32 @@
; OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+; 32-bit Windows adds underscores to C functions, while 64-bit Windows does not.
+%ifidn __OUTPUT_FORMAT__, win32
`); err != nil {
return err
}
for _, symbol := range symbols {
- if _, err := fmt.Fprintf(f, "%%define %s BORINGSSL_PREFIX %%+ %s\n", symbol, symbol); err != nil {
+ if _, err := fmt.Fprintf(f, "%%xdefine _%s _ %%+ BORINGSSL_PREFIX %%+ _%s\n", symbol, symbol); err != nil {
return err
}
}
+ if _, err := fmt.Fprintf(f, "%%else\n"); err != nil {
+ return err
+ }
+
+ for _, symbol := range symbols {
+ if _, err := fmt.Fprintf(f, "%%xdefine %s BORINGSSL_PREFIX %%+ _%s\n", symbol, symbol); err != nil {
+ return err
+ }
+ }
+
+ if _, err := fmt.Fprintf(f, "%%endif\n"); err != nil {
+ return err
+ }
+
return nil
}
diff --git a/util/read_symbols.go b/util/read_symbols.go
index fc3e069..d6d5a9a 100644
--- a/util/read_symbols.go
+++ b/util/read_symbols.go
@@ -20,6 +20,7 @@
"bytes"
"debug/elf"
"debug/macho"
+ "debug/pe"
"flag"
"fmt"
"os"
@@ -33,11 +34,12 @@
const (
ObjFileFormatELF = "elf"
ObjFileFormatMachO = "macho"
+ ObjFileFormatPE = "pe"
)
var (
outFlag = flag.String("out", "-", "File to write output symbols")
- objFileFormat = flag.String("obj-file-format", defaultObjFileFormat(runtime.GOOS), "Object file format to expect (options are elf, macho)")
+ objFileFormat = flag.String("obj-file-format", defaultObjFileFormat(runtime.GOOS), "Object file format to expect (options are elf, macho, pe)")
)
func defaultObjFileFormat(goos string) string {
@@ -46,6 +48,8 @@
return ObjFileFormatELF
case "darwin":
return ObjFileFormatMachO
+ case "windows":
+ return ObjFileFormatPE
default:
// By returning a value here rather than panicking, the user can still
// cross-compile from an unsupported platform to a supported platform by
@@ -105,17 +109,53 @@
}
}
}
+
sort.Strings(symbols)
for _, s := range symbols {
- // Filter out C++ mangled names.
- if !strings.HasPrefix(s, "_Z") {
- if _, err := fmt.Fprintln(out, s); err != nil {
- printAndExit("Error writing to %s: %s", *outFlag, err)
+ var skipSymbols = []string{
+ // Inline functions, etc., from the compiler or language
+ // runtime will naturally end up in the library, to be
+ // deduplicated against other object files. Such symbols
+ // should not be prefixed. It is a limitation of this
+ // symbol-prefixing strategy that we cannot distinguish
+ // our own inline symbols (which should be prefixed)
+ // from the system's (which should not), so we blacklist
+ // known system symbols.
+ "__local_stdio_printf_options",
+ "__local_stdio_scanf_options",
+ "_vscprintf",
+ "_vscprintf_l",
+ "_vsscanf_l",
+ "_xmm",
+ "sscanf",
+ "vsnprintf",
+ // sdallocx is a weak symbol and intended to merge with
+ // the real one, if present.
+ "sdallocx",
+ }
+ var skip bool
+ for _, sym := range skipSymbols {
+ if sym == s {
+ skip = true
+ break
}
}
+ if skip || isCXXSymbol(s) || strings.HasPrefix(s, "__real@") {
+ continue
+ }
+ if _, err := fmt.Fprintln(out, s); err != nil {
+ printAndExit("Error writing to %s: %s", *outFlag, err)
+ }
}
}
+func isCXXSymbol(s string) bool {
+ if *objFileFormat == ObjFileFormatPE {
+ return strings.HasPrefix(s, "?")
+ }
+ return strings.HasPrefix(s, "_Z")
+}
+
// listSymbols lists the exported symbols from an object file.
func listSymbols(contents []byte) ([]string, error) {
switch *objFileFormat {
@@ -123,6 +163,8 @@
return listSymbolsELF(contents)
case ObjFileFormatMachO:
return listSymbolsMachO(contents)
+ case ObjFileFormatPE:
+ return listSymbolsPE(contents)
default:
return nil, fmt.Errorf("unsupported object file format %q", *objFileFormat)
}
@@ -181,3 +223,40 @@
}
return names, nil
}
+
+func listSymbolsPE(contents []byte) ([]string, error) {
+ f, err := pe.NewFile(bytes.NewReader(contents))
+ if err != nil {
+ return nil, err
+ }
+ var ret []string
+ for _, sym := range f.Symbols {
+ const (
+ // https://docs.microsoft.com/en-us/windows/desktop/debug/pe-format#section-number-values
+ IMAGE_SYM_UNDEFINED = 0
+ // https://docs.microsoft.com/en-us/windows/desktop/debug/pe-format#storage-class
+ IMAGE_SYM_CLASS_EXTERNAL = 2
+ )
+ if sym.SectionNumber != IMAGE_SYM_UNDEFINED && sym.StorageClass == IMAGE_SYM_CLASS_EXTERNAL {
+ name := sym.Name
+ if f.Machine == pe.IMAGE_FILE_MACHINE_I386 {
+ // On 32-bit Windows, C symbols are decorated by calling
+ // convention.
+ // https://msdn.microsoft.com/en-us/library/56h2zst2.aspx#FormatC
+ if strings.HasPrefix(name, "_") || strings.HasPrefix(name, "@") {
+ // __cdecl, __stdcall, or __fastcall. Remove the prefix and
+ // suffix, if present.
+ name = name[1:]
+ if idx := strings.LastIndex(name, "@"); idx >= 0 {
+ name = name[:idx]
+ }
+ } else if idx := strings.LastIndex(name, "@@"); idx >= 0 {
+ // __vectorcall. Remove the suffix.
+ name = name[:idx]
+ }
+ }
+ ret = append(ret, name)
+ }
+ }
+ return ret, nil
+}
