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[llvm-objcopy][MachO] Implement --add-section
Reviewers: alexshap, rupprecht, jhenderson Reviewed By: alexshap, jhenderson Subscribers: mgorny, jakehehrlich, abrachet, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66283
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‎llvm/docs/CommandGuide/llvm-objcopy.rst

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@@ -43,6 +43,9 @@ multiple file formats.
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starts with ".note". Otherwise, it will have type `SHT_PROGBITS`. Can be
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specified multiple times to add multiple sections.
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For MachO objects, ``<section>`` must be formatted as
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``<segment name>,<section name>``.
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.. option:: --binary-architecture <arch>, -B
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Ignored for compatibility.

‎llvm/test/tools/llvm-objcopy/MachO/add-section.test

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@@ -0,0 +1,175 @@
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## Show that llvm-objcopy adds a new section into the object if
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## --add-section is given.
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# RUN: yaml2obj --docnum=1 %s -o %t.64bit
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# RUN: yaml2obj --docnum=2 %s -o %t.32bit
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# RUN: echo -n abcdefg > %t.data
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## Error case 1: Nonexistent input file is specified by --add-section.
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# RUN: not llvm-objcopy --add-section __TEXT,__text=%t.missing %t.64bit %t.nonexistent-file 2>&1 \
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# RUN: | FileCheck %s -DINPUT=%t.64bit -DSECTION_DATA_FILE=%t.missing --check-prefix=NONEXSITENT-FILE
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# NONEXSITENT-FILE: error: '[[INPUT]]': '[[SECTION_DATA_FILE]]': {{[Nn]}}o such file or directory
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## Error case 2: Too long segment name.
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# RUN: not llvm-objcopy --add-section __TOOOOOOOOO_LONG,__text=%t.data %t.64bit %t.too-long-seg-name 2>&1 \
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# RUN: | FileCheck %s -DINPUT=%t.64bit --check-prefix=TOO-LONG-SEG-NAME
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# TOO-LONG-SEG-NAME: error: '[[INPUT]]': too long segment name: '__TOOOOOOOOO_LONG'
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## Case 1: Add a new section into an existing segment.
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# RUN: llvm-objcopy --add-section __TEXT,__text=%t.data %t.64bit %t.out1.64bit
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# RUN: llvm-objcopy --add-section __TEXT,__text=%t.data %t.32bit %t.out1.32bit
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# RUN: llvm-readobj --sections --section-data %t.out1.64bit \
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# RUN: | FileCheck %s --check-prefixes=64BIT,COMMON,CASE1
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# RUN: llvm-readobj --sections --section-data %t.out1.32bit \
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# RUN: | FileCheck %s --check-prefixes=32BIT,COMMON,CASE1
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## Case 2: Add a new section into a nonexistent segment.
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# RUN: llvm-objcopy --add-section __FOO,__bar=%t.data %t.64bit %t.out2.64bit
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# RUN: llvm-objcopy --add-section __FOO,__bar=%t.data %t.32bit %t.out2.32bit
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# RUN: llvm-readobj --sections --section-data --macho-segment %t.out2.64bit \
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# RUN: | FileCheck %s --check-prefixes=64BIT,COMMON,CASE2,CASE2-64BIT
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# RUN: llvm-readobj --sections --section-data --macho-segment %t.out2.32bit \
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# RUN: | FileCheck %s --check-prefixes=32BIT,COMMON,CASE2,CASE2-32BIT
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## Case 3: Add a new section with /dev/null.
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# RUN: llvm-objcopy --add-section __TEXT,__text=/dev/null %t.64bit %t.devnull
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# RUN: llvm-readobj --sections --section-data %t.devnull \
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# RUN: | FileCheck %s --check-prefixes=64BIT,COMMON,DEVNULL
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## 64-bit binary
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--- !mach-o
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FileHeader:
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magic: 0xFEEDFACF
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cputype: 0x01000007
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cpusubtype: 0x00000003
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filetype: 0x00000001
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ncmds: 1
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sizeofcmds: 152
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flags: 0x00002000
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reserved: 0x00000000
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LoadCommands:
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- cmd: LC_SEGMENT_64
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cmdsize: 152
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segname: ''
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vmaddr: 0
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vmsize: 4
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fileoff: 184
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filesize: 4
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maxprot: 7
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initprot: 7
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nsects: 1
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flags: 0
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Sections:
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- sectname: __text
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segname: __TEXT
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addr: 0x0000000000000000
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content: 'AABBCCDD'
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size: 4
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offset: 184
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align: 0
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reloff: 0x00000000
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nreloc: 0
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flags: 0x80000400
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reserved1: 0x00000000
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reserved2: 0x00000000
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reserved3: 0x00000000
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## 32-bit binary
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--- !mach-o
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FileHeader:
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magic: 0xFEEDFACE
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cputype: 0x00000007
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cpusubtype: 0x00000003
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filetype: 0x00000001
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ncmds: 1
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sizeofcmds: 124
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flags: 0x00002000
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LoadCommands:
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- cmd: LC_SEGMENT
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cmdsize: 124
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segname: ''
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vmaddr: 0
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vmsize: 4
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fileoff: 184
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filesize: 4
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maxprot: 7
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initprot: 7
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nsects: 1
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flags: 0
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Sections:
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- sectname: __text
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segname: __TEXT
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addr: 0x0000000000000000
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content: 'AABBCCDD'
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size: 4
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offset: 184
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align: 0
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reloff: 0x00000000
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nreloc: 0
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flags: 0x80000400
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reserved1: 0x00000000
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reserved2: 0x00000000
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reserved3: 0x00000000
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# COMMON: Index: 0
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# COMMON-NEXT: __text (5F 5F 74 65 78 74 00 00 00 00 00 00 00 00 00 00)
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# COMMON-NEXT: Segment: __TEXT (5F 5F 54 45 58 54 00 00 00 00 00 00 00 00 00 00)
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# COMMON: Index: 1
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# CASE1-NEXT: __text (5F 5F 74 65 78 74 00 00 00 00 00 00 00 00 00 00)
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# CASE1-NEXT: Segment: __TEXT (5F 5F 54 45 58 54 00 00 00 00 00 00 00 00 00 00)
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# CASE2-NEXT: Name: __bar (5F 5F 62 61 72 00 00 00 00 00 00 00 00 00 00 00)
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# CASE2-NEXT: Segment: __FOO (5F 5F 46 4F 4F 00 00 00 00 00 00 00 00 00 00 00)
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# DEVNULL-NEXT: __text (5F 5F 74 65 78 74 00 00 00 00 00 00 00 00 00 00)
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# DEVNULL-NEXT: Segment: __TEXT (5F 5F 54 45 58 54 00 00 00 00 00 00 00 00 00 00)
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# COMMON-NEXT: Address: 0x0
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# CASE1-NEXT: Size: 0x7
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# CASE2-NEXT: Size: 0x7
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# DEVNULL-NEXT: Size: 0x0
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# 64BIT-NEXT: Offset: 340
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# 32BIT-NEXT: Offset: 280
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# COMMON-NEXT: Alignment: 0
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# COMMON-NEXT: RelocationOffset: 0x0
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# COMMON-NEXT: RelocationCount: 0
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# COMMON-NEXT: Type: Regular (0x0)
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# COMMON-NEXT: Attributes [ (0x0)
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# COMMON-NEXT: ]
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# COMMON-NEXT: Reserved1: 0x0
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# COMMON-NEXT: Reserved2: 0x0
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# 64BIT-NEXT: Reserved3: 0x0
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# COMMON-NEXT: SectionData (
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# CASE1-NEXT: 0000: 61626364 656667 |abcdefg|
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# CASE2-NEXT: 0000: 61626364 656667 |abcdefg|
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# COMMON-NEXT: )
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# CASE2: Segment {
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# CASE2-64BIT-NEXT: Cmd: LC_SEGMENT_64
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# CASE2-32BIT-NEXT: Cmd: LC_SEGMENT{{$}}
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# CASE2-NEXT: Name:
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# CASE2-64BIT-NEXT: Size: 152
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# CASE2-32BIT-NEXT: Size: 124
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# CASE2-NEXT: vmaddr: 0x0
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# CASE2-NEXT: vmsize: 0x4
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# CASE2-64BIT-NEXT: fileoff: 336
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# CASE2-32BIT-NEXT: fileoff: 276
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# CASE2-NEXT: filesize: 4
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# CASE2-NEXT: maxprot: rwx
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# CASE2-NEXT: initprot: rwx
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# CASE2-NEXT: nsects: 1
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# CASE2-NEXT: flags: 0x0
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# CASE2-NEXT: }
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# CASE2-NEXT: Segment {
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# CASE2-64BIT-NEXT: Cmd: LC_SEGMENT_64
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# CASE2-32BIT-NEXT: Cmd: LC_SEGMENT{{$}}
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# CASE2-NEXT: Name: __FOO
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# CASE2-64BIT-NEXT: Size: 152
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# CASE2-32BIT-NEXT: Size: 124
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# CASE2-NEXT: vmaddr: 0x0
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# CASE2-NEXT: vmsize: 0x7
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# CASE2-64BIT-NEXT: fileoff: 340
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# CASE2-32BIT-NEXT: fileoff: 280
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# CASE2-NEXT: filesize: 7
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# CASE2-NEXT: maxprot: ---
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# CASE2-NEXT: initprot: ---
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# CASE2-NEXT: nsects: 1
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# CASE2-NEXT: flags: 0x0
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# CASE2-NEXT: }

‎llvm/tools/llvm-objcopy/MachO/MachOObjcopy.cpp

Lines changed: 65 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -106,15 +106,65 @@ static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
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SecName.str().c_str());
107107
}
108108

109+
static Error addSection(StringRef SecName, StringRef Filename, Object &Obj) {
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ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
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MemoryBuffer::getFile(Filename);
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if (!BufOrErr)
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return createFileError(Filename, errorCodeToError(BufOrErr.getError()));
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std::unique_ptr<MemoryBuffer> Buf = std::move(*BufOrErr);
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std::pair<StringRef, StringRef> Pair = SecName.split(',');
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StringRef TargetSegName = Pair.first;
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Section Sec(TargetSegName, Pair.second);
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Sec.Content = Obj.NewSectionsContents.save(Buf->getBuffer());
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// Add the a section into an existing segment.
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for (LoadCommand &LC : Obj.LoadCommands) {
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Optional<StringRef> SegName = LC.getSegmentName();
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if (SegName && SegName == TargetSegName) {
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LC.Sections.push_back(Sec);
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return Error::success();
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}
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}
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// There's no segment named TargetSegName. Create a new load command and
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// Insert a new section into it.
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LoadCommand &NewSegment = Obj.addSegment(TargetSegName);
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NewSegment.Sections.push_back(Sec);
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return Error::success();
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}
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// isValidMachOCannonicalName returns success if Name is a MachO cannonical name
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// ("<segment>,<section>") and lengths of both segment and section names are
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// valid.
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Error isValidMachOCannonicalName(StringRef Name) {
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if (Name.count(',') != 1)
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return createStringError(errc::invalid_argument,
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"invalid section name '%s' (should be formatted "
144+
"as '<segment name>,<section name>')",
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Name.str().c_str());
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std::pair<StringRef, StringRef> Pair = Name.split(',');
148+
if (Pair.first.size() > 16)
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return createStringError(errc::invalid_argument,
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"too long segment name: '%s'",
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Pair.first.str().c_str());
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if (Pair.second.size() > 16)
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return createStringError(errc::invalid_argument,
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"too long section name: '%s'",
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Pair.second.str().c_str());
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return Error::success();
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}
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static Error handleArgs(const CopyConfig &Config, Object &Obj) {
110160
if (Config.AllowBrokenLinks || !Config.BuildIdLinkDir.empty() ||
111161
Config.BuildIdLinkInput || Config.BuildIdLinkOutput ||
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!Config.SplitDWO.empty() || !Config.SymbolsPrefix.empty() ||
113-
!Config.AllocSectionsPrefix.empty() || !Config.AddSection.empty() ||
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!Config.KeepSection.empty() || Config.NewSymbolVisibility ||
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!Config.SymbolsToGlobalize.empty() || !Config.SymbolsToKeep.empty() ||
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!Config.SymbolsToLocalize.empty() || !Config.SymbolsToWeaken.empty() ||
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!Config.SymbolsToKeepGlobal.empty() || !Config.SectionsToRename.empty() ||
163+
!Config.AllocSectionsPrefix.empty() || !Config.KeepSection.empty() ||
164+
Config.NewSymbolVisibility || !Config.SymbolsToGlobalize.empty() ||
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!Config.SymbolsToKeep.empty() || !Config.SymbolsToLocalize.empty() ||
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!Config.SymbolsToWeaken.empty() || !Config.SymbolsToKeepGlobal.empty() ||
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!Config.SectionsToRename.empty() ||
118168
!Config.UnneededSymbolsToRemove.empty() ||
119169
!Config.SetSectionAlignment.empty() || !Config.SetSectionFlags.empty() ||
120170
Config.ExtractDWO || Config.KeepFileSymbols || Config.LocalizeHidden ||
@@ -148,6 +198,16 @@ static Error handleArgs(const CopyConfig &Config, Object &Obj) {
148198
return E;
149199
}
150200

201+
for (const auto &Flag : Config.AddSection) {
202+
std::pair<StringRef, StringRef> SecPair = Flag.split("=");
203+
StringRef SecName = SecPair.first;
204+
StringRef File = SecPair.second;
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if (Error E = isValidMachOCannonicalName(SecName))
206+
return E;
207+
if (Error E = addSection(SecName, File, Obj))
208+
return E;
209+
}
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151211
for (StringRef RPath : Config.RPathToAdd) {
152212
for (LoadCommand &LC : Obj.LoadCommands) {
153213
if (LC.MachOLoadCommand.load_command_data.cmd == MachO::LC_RPATH &&

‎llvm/tools/llvm-objcopy/MachO/MachOReader.cpp

Lines changed: 3 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -29,13 +29,9 @@ void MachOReader::readHeader(Object &O) const {
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template <typename SectionType>
3131
Section constructSectionCommon(SectionType Sec) {
32-
Section S;
33-
S.Sectname =
34-
StringRef(Sec.sectname, strnlen(Sec.sectname, sizeof(Sec.sectname)))
35-
.str();
36-
S.Segname =
37-
StringRef(Sec.segname, strnlen(Sec.segname, sizeof(Sec.sectname))).str();
38-
S.CanonicalName = (Twine(S.Segname) + "," + S.Sectname).str();
32+
StringRef SegName(Sec.segname, strnlen(Sec.segname, sizeof(Sec.segname)));
33+
StringRef SectName(Sec.sectname, strnlen(Sec.sectname, sizeof(Sec.sectname)));
34+
Section S(SegName, SectName);
3935
S.Addr = Sec.addr;
4036
S.Size = Sec.size;
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S.Offset = Sec.offset;

‎llvm/tools/llvm-objcopy/MachO/Object.cpp

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Original file line numberDiff line numberDiff line change
@@ -33,6 +33,47 @@ void Object::addLoadCommand(LoadCommand LC) {
3333
LoadCommands.push_back(std::move(LC));
3434
}
3535

36+
template <typename SegmentType>
37+
static void constructSegment(SegmentType &Seg,
38+
llvm::MachO::LoadCommandType CmdType,
39+
StringRef SegName) {
40+
assert(SegName.size() <= sizeof(Seg.segname) && "too long segment name");
41+
memset(&Seg, 0, sizeof(SegmentType));
42+
Seg.cmd = CmdType;
43+
strncpy(Seg.segname, SegName.data(), SegName.size());
44+
}
45+
46+
LoadCommand &Object::addSegment(StringRef SegName) {
47+
LoadCommand LC;
48+
if (is64Bit())
49+
constructSegment(LC.MachOLoadCommand.segment_command_64_data,
50+
MachO::LC_SEGMENT_64, SegName);
51+
else
52+
constructSegment(LC.MachOLoadCommand.segment_command_data,
53+
MachO::LC_SEGMENT, SegName);
54+
55+
LoadCommands.push_back(LC);
56+
return LoadCommands.back();
57+
}
58+
59+
/// Extracts a segment name from a string which is possibly non-null-terminated.
60+
static StringRef extractSegmentName(const char *SegName) {
61+
return StringRef(SegName,
62+
strnlen(SegName, sizeof(MachO::segment_command::segname)));
63+
}
64+
65+
Optional<StringRef> LoadCommand::getSegmentName() const {
66+
const MachO::macho_load_command &MLC = MachOLoadCommand;
67+
switch (MLC.load_command_data.cmd) {
68+
case MachO::LC_SEGMENT:
69+
return extractSegmentName(MLC.segment_command_data.segname);
70+
case MachO::LC_SEGMENT_64:
71+
return extractSegmentName(MLC.segment_command_64_data.segname);
72+
default:
73+
return None;
74+
}
75+
}
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3677
} // end namespace macho
3778
} // end namespace objcopy
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} // end namespace llvm

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