cmd/link/internal/ld: don't leave files open in a loop

Noticed by Ingo Oeser in his review of CL 168321.

Change-Id: I2f39db675a7c22b395062a11903657a9d0d1956d
Reviewed-on: https://go-review.googlesource.com/c/go/+/168560
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/cmd/link/internal/ld/macho.go b/src/cmd/link/internal/ld/macho.go
index 98359c26fcc94cb484a42d986a63f9592bb97e3b..d13857081a24354e941f6f3fd120ff995830b739 100644 (file)
--- a/src/cmd/link/internal/ld/macho.go
+++ b/src/cmd/link/internal/ld/macho.go
@@ -694,14 +694,20 @@ func Asmbmacho(ctxt *Link) {
                        }
                }
        }
-       load, err := hostobjMachoPlatform(hostobj)
-       if err != nil {
-               Exitf("%v", err)
+       foundLoad := false
+       for _, h := range hostobj {
+               load, err := hostobjMachoPlatform(&h)
+               if err != nil {
+                       Exitf("%v", err)
+               }
+               if load != nil {
+                       ml := newMachoLoad(ctxt.Arch, load.cmd.type_, uint32(len(load.cmd.data)))
+                       copy(ml.data, load.cmd.data)
+                       foundLoad = true
+                       break
+               }
        }
-       if load != nil {
-               ml := newMachoLoad(ctxt.Arch, load.cmd.type_, uint32(len(load.cmd.data)))
-               copy(ml.data, load.cmd.data)
-       } else if ctxt.LinkMode == LinkInternal {
+       if !foundLoad && ctxt.LinkMode == LinkInternal {
                // For lldb, must say LC_VERSION_MIN_MACOSX or else
                // it won't know that this Mach-O binary is from OS X
                // (could be iOS or WatchOS instead).
@@ -1027,29 +1033,20 @@ func Machoemitreloc(ctxt *Link) {
 }
 
 // hostobjMachoPlatform returns the first platform load command found
-// in the host objects, if any.
-func hostobjMachoPlatform(hostobj []Hostobj) (*MachoPlatformLoad, error) {
-       for _, h := range hostobj {
-               f, err := os.Open(h.file)
-               if err != nil {
-                       return nil, fmt.Errorf("%s: failed to open host object: %v\n", h.file, err)
-               }
-               defer f.Close()
-               sr := io.NewSectionReader(f, h.off, h.length)
-               m, err := macho.NewFile(sr)
-               if err != nil {
-                       // Not a valid Mach-O file.
-                       return nil, nil
-               }
-               load, err := peekMachoPlatform(m)
-               if err != nil {
-                       return nil, err
-               }
-               if load != nil {
-                       return load, nil
-               }
+// in the host object, if any.
+func hostobjMachoPlatform(h *Hostobj) (*MachoPlatformLoad, error) {
+       f, err := os.Open(h.file)
+       if err != nil {
+               return nil, fmt.Errorf("%s: failed to open host object: %v\n", h.file, err)
        }
-       return nil, nil
+       defer f.Close()
+       sr := io.NewSectionReader(f, h.off, h.length)
+       m, err := macho.NewFile(sr)
+       if err != nil {
+               // Not a valid Mach-O file.
+               return nil, nil
+       }
+       return peekMachoPlatform(m)
 }
 
 // peekMachoPlatform returns the first LC_VERSION_MIN_* or LC_BUILD_VERSION