MachO no longer needs contiguous LC_SEGMENT (SourceForge bug 3308161)

src/p_lx_elf.cpp

@@ -85,6 +85,52 @@ fpad4(OutputFile *fo)
     return d + len;
 }
 
+void
+PackLinuxElf32::hemfix(Elf32_Phdr *phdr, unsigned n_phdr)
+{
+    unsigned j;
+    for (j=0; j < n_phdr; ++phdr, ++j) {
+        unsigned const mask = -phdr->p_align;
+        if (PT_LOAD32==phdr->p_type) {  /* first PT_LOAD */
+            if (~mask & phdr->p_vaddr
+            &&  0==(~mask & (phdr->p_vaddr - phdr->p_offset))) {
+                unsigned const hem = ~mask & phdr->p_offset;
+                phdr->p_offset -= hem;
+                phdr->p_vaddr  -= hem;
+                if (phdr->p_paddr)
+                    phdr->p_paddr  -= hem;
+                phdr->p_filesz += hem;
+                phdr->p_memsz  += hem;
+            }
+            break;
+        }
+    }
+    return;
+}
+
+void
+PackLinuxElf64::hemfix(Elf64_Phdr *phdr, unsigned n_phdr)
+{
+    unsigned j;
+    for (j=0; j < n_phdr; ++phdr, ++j) {
+        unsigned const mask = -phdr->p_align;
+        if (PT_LOAD64==phdr->p_type) {  /* first PT_LOAD */
+            if (~mask & phdr->p_vaddr
+            &&  0==(~mask & (phdr->p_vaddr - phdr->p_offset))) {
+                unsigned const hem = ~mask & phdr->p_offset;
+                phdr->p_offset -= hem;
+                phdr->p_vaddr  -= hem;
+                if (phdr->p_paddr)
+                    phdr->p_paddr  -= hem;
+                phdr->p_filesz += hem;
+                phdr->p_memsz  += hem;
+            }
+            break;
+        }
+    }
+    return;
+}
+
 int
 PackLinuxElf32::checkEhdr(Elf32_Ehdr const *ehdr) const
 {
@@ -1240,7 +1286,8 @@ bool PackLinuxElf32::canPack()
 
     unsigned osabi0 = u.buf[Elf32_Ehdr::EI_OSABI];
     // The first PT_LOAD32 must cover the beginning of the file (0==p_offset).
-    Elf32_Phdr const *phdr = (Elf32_Phdr const *)(u.buf + e_phoff);
+    Elf32_Phdr *phdr = (Elf32_Phdr *)(u.buf + e_phoff);
+    hemfix(phdr, umin(14, e_phnum));
     note_size = 0;
     for (unsigned j=0; j < e_phnum; ++phdr, ++j) {
         if (j >= 14) {
@@ -1476,16 +1523,16 @@ PackLinuxElf64amd::canPack()
     }
 
     // The first PT_LOAD64 must cover the beginning of the file (0==p_offset).
-    Elf64_Phdr const *phdr = (Elf64_Phdr const *)(u.buf + (unsigned) e_phoff);
+    Elf64_Phdr *phdr = (Elf64_Phdr *)(u.buf + e_phoff);
+    hemfix(phdr, umin(14, e_phnum));
     for (unsigned j=0; j < e_phnum; ++phdr, ++j) {
         if (j >= 14)
             return false;
         if (phdr->PT_LOAD64 == get_te32(&phdr->p_type)) {
-            // Just avoid the "rewind" when unpacking?
+            if (phdr->p_offset != 0) {
-            //if (phdr->p_offset != 0) {
+                throwCantPack("invalid Phdr p_offset; try '--force-execve'");
-            //    throwCantPack("invalid Phdr p_offset; try '--force-execve'");
+                return false;
-            //    return false;
+            }
-            //}
             load_va = get_te64(&phdr->p_vaddr);
             exetype = 1;
             break;
@@ -1974,6 +2021,7 @@ void PackLinuxElf32::pack1(OutputFile *fo, Filter & /*ft*/)
     phdri = new Elf32_Phdr[e_phnum];
     fi->seek(e_phoff, SEEK_SET);
     fi->readx(phdri, sz_phdrs);
+    hemfix(phdri, e_phnum);
 
     // Remember all PT_NOTE, and find lg2_page from PT_LOAD.
     Elf32_Phdr const *phdr = phdri;
@@ -2163,6 +2211,7 @@ void PackLinuxElf64::pack1(OutputFile *fo, Filter & /*ft*/)
     phdri = new Elf64_Phdr[e_phnum];
     fi->seek(e_phoff, SEEK_SET);
     fi->readx(phdri, sz_phdrs);
+    hemfix(phdri, e_phnum);
 
     Elf64_Phdr const *phdr = phdri;
     note_size = 0;

src/p_lx_elf.h

@@ -101,6 +101,7 @@ public:
     PackLinuxElf32(InputFile *f);
     virtual ~PackLinuxElf32();
 protected:
+    void hemfix(Elf32_Phdr *phdr, unsigned n_phdr);
     virtual int checkEhdr(Elf32_Ehdr const *ehdr) const;
     virtual bool canPack();
 
@@ -225,6 +226,7 @@ public:
     /*virtual void buildLoader(const Filter *);*/
 
 protected:
+    void hemfix(Elf64_Phdr *phdr, unsigned n_phdr);
     virtual int checkEhdr(Elf64_Ehdr const *ehdr) const;
 
     virtual void pack1(OutputFile *, Filter &);  // generate executable header

src/p_mach.cpp

@@ -1376,7 +1376,7 @@ bool PackMachBase<T>::canPack()
     // Put LC_SEGMENT together at the beginning, ascending by .vmaddr.
     qsort(msegcmd, ncmds, sizeof(*msegcmd), compare_segment_command);
 
-    // Check that LC_SEGMENTs form one contiguous chunk of the file.
+    // Check alignment of non-null LC_SEGMENT.
     for (unsigned j= 0; j < ncmds; ++j) {
         if (lc_seg==msegcmd[j].cmd) {
             if (~PAGE_MASK & (msegcmd[j].fileoff | msegcmd[j].vmaddr)) {
@@ -1384,13 +1384,11 @@ bool PackMachBase<T>::canPack()
             }
             if (msegcmd[j].vmsize==0)
                 break;  // was sorted last
-            if (0 < j) {
+
-                unsigned const sz = PAGE_MASK
+            // We used to check that LC_SEGMENTS were contiguous,
-                                  & (~PAGE_MASK + msegcmd[j-1].filesize);
+            // but apparently that is not needed anymore,
-                if ((sz + msegcmd[j-1].fileoff)!=msegcmd[j].fileoff) {
+            // and Google compilers generate strange layouts.
-                    return false;
+
-                }
-            }
             ++n_segment;
             sz_segment = msegcmd[j].filesize + msegcmd[j].fileoff - msegcmd[0].fileoff;
         }