[llvm-readelf/obj] - Refine the error message about the broken string table.

[grimar]

Summary

This:

1. Changes reportWarning to reportUniqueWarning (no-op here).
2. Adds more context to the message.
3. Merges broken-dynsym-link.test into dyn-symbols.test, adds more testing.

[MaskRay]

llvm/tools/llvm-readobj/ELFDumper.cpp

2047–2048

Other messages don't prepend the

[jhenderson]

LGTM.

[grimar]

llvm/tools/llvm-readobj/ELFDumper.cpp

2047–2048

You mean before "decribe(Sec)"? In a few places we have it.

llvm/test/tools/llvm-readobj/ELF/broken-dynsym-link.test

-## Test that we are able to dump section headers even if the
-## .dynsym section's sh_link field is broken.
-
-## Case 1: sh_link is set to 0.
-# RUN: yaml2obj --docnum=1 -DLINK=0 %s -o %t1
-# RUN: llvm-readobj -S %t1 2>&1 | FileCheck %s -DFILE=%t1 --check-prefixes=LLVM,ERR
-# RUN: llvm-readelf -S %t1 2>&1 | FileCheck %s -DFILE=%t1 --check-prefixes=GNU,ERR
-
-# ERR: warning: '[[FILE]]': invalid sh_type for string table section [index 0]: expected SHT_STRTAB, but got SHT_NULL
-
-# LLVM:      Name: .dynsym
-# LLVM-NEXT:  Type: SHT_DYNSYM
-# LLVM-NEXT:  Flags [
-# LLVM-NEXT:    SHF_ALLOC
-# LLVM-NEXT:  ]
-# LLVM-NEXT:  Address: 0x0
-# LLVM-NEXT:  Offset: 0x40
-# LLVM-NEXT:  Size: 24
-# LLVM-NEXT:  Link: 0
-
-# GNU:      Section Headers:
-# GNU-NEXT:  [Nr] Name    Type   Address          Off    Size   ES Flg Lk
-# GNU-NEXT:  [ 0]         NULL   0000000000000000 000000 000000 00 0   0
-# GNU-NEXT:  [ 1] .dynsym DYNSYM 0000000000000000 000040 000018 18 A   0
-
---- !ELF
-FileHeader:
-  Class: ELFCLASS64
-  Data:  ELFDATA2LSB
-  Type:  ET_DYN
-Sections:
-  - Name: .dynsym
-    Type: SHT_DYNSYM
-    Link: [[LINK]]
-
-## Case 2: sh_link is set to 255, which is larger than the number of the sections.
-# RUN: yaml2obj --docnum=1 -DLINK=255 %s -o %t2
-
-# RUN: llvm-readobj -S %t2 2>&1 | FileCheck -DFILE=%t2 %s --check-prefixes=LLVM2,ERR2
-# RUN: llvm-readelf -S %t2 2>&1 | FileCheck -DFILE=%t2 %s --check-prefixes=GNU2,ERR2
-
-# ERR2: warning: '[[FILE]]': invalid section index: 255
-
-# LLVM2:      Name: .dynsym
-# LLVM2-NEXT:  Type: SHT_DYNSYM
-# LLVM2-NEXT:  Flags [
-# LLVM2-NEXT:    SHF_ALLOC
-# LLVM2-NEXT:  ]
-# LLVM2-NEXT:  Address: 0x0
-# LLVM2-NEXT:  Offset: 0x40
-# LLVM2-NEXT:  Size: 24
-# LLVM2-NEXT:  Link: 255
-
-# GNU2:      Section Headers:
-# GNU2-NEXT:  [Nr] Name    Type   Address          Off    Size   ES Flg Lk
-# GNU2-NEXT:  [ 0]         NULL   0000000000000000 000000 000000 00 0   0
-# GNU2-NEXT:  [ 1] .dynsym DYNSYM 0000000000000000 000040 000018 18 A   255

llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test

 FileHeader:
   Class: ELFCLASS32
   Data:  ELFDATA2LSB
   Type:  ET_DYN
 Sections:
   - Name:     .dynsym
     Type:     SHT_DYNSYM
     EntSize:  [[ENTSIZE=<none>]]
+    Link:     [[LINK=<none>]]
     ShOffset: [[OFFSET=<none>]]
     ShSize:   [[SIZE=<none>]]
 DynamicSymbols:
   - Name: foo
 
 ## b) check we report a warning when the sh_offset field of the SHT_DYNSYM section is
 ##    invalid (sh_offset + sh_size is greater than the file size). Check we don't dump
 ##    dynamic symbols in this case.

 # RUN:   --check-prefixes=SIZE-BROKEN,SIZE-BROKEN-LLVM
 # RUN: llvm-readelf %t15.size --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t15.size \
 # RUN:   --implicit-check-not="Symbol table" --check-prefix=SIZE-BROKEN
 
 # SIZE-BROKEN: warning: '[[FILE]]': unable to read dynamic symbols from SHT_DYNSYM section with index 1: offset (0x34) + size (0xffffffff) is greater than the file size (0x148)
 
 # SIZE-BROKEN-LLVM:      DynamicSymbols [
 # SIZE-BROKEN-LLVM-NEXT: ]
+
+## d) check we report a warning when the sh_link field of the SHT_DYNSYM section
+##    is not a valid section index or is not an index of a valid string table.
+# RUN: yaml2obj --docnum=14 %s -DLINK=0xffffffff -o %t16.link
+# RUN: llvm-readobj %t16.link --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link \
+# RUN:   --check-prefixes=LINK-BROKEN1,LINK-BROKEN-LLVM --implicit-check-not=warning:
+# RUN: llvm-readelf %t16.link --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link \
+# RUN:   --check-prefixes=LINK-BROKEN1,LINK-BROKEN-GNU --implicit-check-not=warning:
+
+## Also test that we are able to dump section headers even if the .dynsym section's sh_link field is broken.
+# RUN: llvm-readobj %t16.link --section-headers --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link \
+# RUN:   --check-prefixes=LINK-BROKEN1,LINK-SEC-HDRS-LLVM,LINK-BROKEN-LLVM --implicit-check-not=warning:
+# RUN: llvm-readelf %t16.link --section-headers --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link \
+# RUN:   --check-prefixes=LINK-BROKEN1,LINK-SEC-HDRS-GNU,LINK-BROKEN-GNU
+
+# RUN: yaml2obj --docnum=14 %s -DLINK=0x0 -o %t16.link.0
+# RUN: llvm-readobj %t16.link.0 --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link.0 \
+# RUN:   --check-prefixes=LINK-BROKEN2,LINK-BROKEN-LLVM --implicit-check-not=warning:
+# RUN: llvm-readelf %t16.link.0 --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link.0 \
+# RUN:   --check-prefixes=LINK-BROKEN2,LINK-BROKEN-GNU --implicit-check-not=warning:
+
+## Also test that we are able to dump section headers even if the .dynsym section's sh_link field is broken.
+# RUN: llvm-readobj %t16.link.0 --section-headers --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link.0 \
+# RUN:   --check-prefixes=LINK-BROKEN2,LINK-SEC-HDRS-LLVM,LINK-BROKEN-LLVM --implicit-check-not=warning:
+# RUN: llvm-readelf %t16.link.0 --section-headers --dyn-symbols 2>&1 | FileCheck %s -DFILE=%t16.link.0 \
+# RUN:   --check-prefixes=LINK-BROKEN2,LINK-SEC-HDRS-GNU,LINK-BROKEN-GNU --implicit-check-not=warning:
+
+# LINK-BROKEN1: warning: '[[FILE]]': unable to get the string table for the SHT_DYNSYM section with index 1: invalid section index: 4294967295
+# LINK-BROKEN2: warning: '[[FILE]]': unable to get the string table for the SHT_DYNSYM section with index 1: invalid sh_type for string table section [index 0]: expected SHT_STRTAB, but got SHT_NULL
+
+# LINK-SEC-HDRS-LLVM: Sections [
+# LINK-SEC-HDRS-GNU:  There are 5 section headers, starting at offset 0x80:
+
+# LINK-BROKEN-LLVM:      DynamicSymbols [
+# LINK-BROKEN-LLVM-NEXT: warning: '[[FILE]]': st_name (0x0) is past the end of the string table of size 0x0
+# LINK-BROKEN-LLVM-NEXT:   Symbol {
+# LINK-BROKEN-LLVM-NEXT:     Name: <?> (0)
+# LINK-BROKEN-LLVM-NEXT:     Value: 0x0
+# LINK-BROKEN-LLVM-NEXT:     Size: 0
+# LINK-BROKEN-LLVM-NEXT:     Binding: Local (0x0)
+# LINK-BROKEN-LLVM-NEXT:     Type: None (0x0)
+# LINK-BROKEN-LLVM-NEXT:     Other: 0
+# LINK-BROKEN-LLVM-NEXT:     Section: Undefined (0x0)
+# LINK-BROKEN-LLVM-NEXT:   }
+# LINK-BROKEN-LLVM-NEXT: warning: '[[FILE]]': st_name (0x1) is past the end of the string table of size 0x0
+# LINK-BROKEN-LLVM-NEXT:   Symbol {
+# LINK-BROKEN-LLVM-NEXT:     Name: <?> (1)
+# LINK-BROKEN-LLVM-NEXT:     Value: 0x0
+# LINK-BROKEN-LLVM-NEXT:     Size: 0
+# LINK-BROKEN-LLVM-NEXT:     Binding: Local (0x0)
+# LINK-BROKEN-LLVM-NEXT:     Type: None (0x0)
+# LINK-BROKEN-LLVM-NEXT:     Other: 0
+# LINK-BROKEN-LLVM-NEXT:     Section: Undefined (0x0)
+# LINK-BROKEN-LLVM-NEXT:   }
+# LINK-BROKEN-LLVM-NEXT: ]
+
+# LINK-BROKEN-GNU:      Symbol table '.dynsym' contains 2 entries:
+# LINK-BROKEN-GNU-NEXT:    Num:    Value  Size Type    Bind   Vis       Ndx Name
+# LINK-BROKEN-GNU-NEXT: warning: '[[FILE]]': st_name (0x0) is past the end of the string table of size 0x0
+# LINK-BROKEN-GNU-NEXT:      0: 00000000     0 NOTYPE  LOCAL  DEFAULT   UND <?>
+# LINK-BROKEN-GNU-NEXT: warning: '[[FILE]]': st_name (0x1) is past the end of the string table of size 0x0
+# LINK-BROKEN-GNU-NEXT:      1: 00000000     0 NOTYPE  LOCAL  DEFAULT   UND <?>

llvm/tools/llvm-readobj/ELFDumper.cpp

case ELF::SHT_DYNSYM:
             createDRI(Sec.sh_offset, Sec.sh_size, Sec.sh_entsize);
         if (RegOrErr) {
           DynSymRegion = *RegOrErr;
           DynSymRegion->Context = describe(Sec);
 
           if (Expected<StringRef> E = Obj.getStringTableForSymtab(Sec))
             DynamicStringTable = *E;
           else
-            reportWarning(E.takeError(), ObjF.getFileName());
+            reportUniqueWarning("unable to get the string table for the " +
+                                describe(Sec) + ": " + toString(E.takeError()));
         } else {
           reportUniqueWarning("unable to read dynamic symbols from " +
                               describe(Sec) + ": " +
                               toString(RegOrErr.takeError()));
         }
       }
       break;
     case ELF::SHT_SYMTAB_SHNDX: