BUILD: sym: Get it to build and work on various OSes

Define NT_GNU_BUILD_ID and STT_GNU_IFUNC, as those are GNU extensions,
and not every OS defines it.
Define ElfW() if it is not provided by the OS already.
Make sure sections are actually readable, as sometimes they are not on
OpenBSD.
The NetBSD linker does not use an empty name for the executable, so
don't recognize it that way. However, every OS will provide the
executable first, so rely on that instead.

With those changes, this builds and works on NetBSD, OpenBSD and
Solaris/Illumos.

diff --git a/src/sym.c b/src/sym.c
index 41f034a2612a181280197788a491ab7824299cc0..38ab98b8f15c6c3bb3233348a68bbbbf5ff46f69 100644 (file)
--- a/src/sym.c
+++ b/src/sym.c
@@ -155,6 +155,7 @@ struct sym_build {
        struct sym_obj **objs;     /* objects created this build, handed to the snapshot */
        unsigned int nobjs, oalloc;
        int oom;                   /* set on any allocation failure */
+       int seen_exe;              /* set once the executable was passed to phdr_cb */
 };
 
 /* records an object created this build; returns 0 on success, -1 on OOM */
@@ -278,6 +279,14 @@ int sym_add_debug_dir(const char *dir)
 #include <haproxy/net_helper.h>
 #include <import/xz.h>
 
+/* Some ELF platforms (e.g. Solaris) do not define GNU extensions. */
+#ifndef NT_GNU_BUILD_ID
+#define NT_GNU_BUILD_ID 3
+#endif
+#ifndef STT_GNU_IFUNC
+#define STT_GNU_IFUNC 10
+#endif
+
 /* Largest decompressed symbol table we accept, and largest LZMA2 dictionary we
  * let the decoder allocate for it.
  */
@@ -305,9 +314,15 @@ static const struct {
  * toolchain since glibc doesn't provide *_NATIVE convenience macros.
  */
 #if __WORDSIZE == 64
+# ifndef ElfW
+#  define ElfW(type) Elf64_##type
+# endif
 # define SYM_ELFCLASS    ELFCLASS64
 # define SYM_ST_TYPE(i)  ELF64_ST_TYPE(i)
 #else
+# ifndef ElfW
+#  define ElfW(type) Elf32_##type
+# endif
 # define SYM_ELFCLASS    ELFCLASS32
 # define SYM_ST_TYPE(i)  ELF32_ST_TYPE(i)
 #endif
@@ -786,6 +801,8 @@ static const unsigned char *mem_build_id(const ElfW(Phdr) *phdr, unsigned int ph
                /* entries are padded to the segment's alignment, 4 or 8 */
                align = phdr[i].p_align == 8 ? 8 : 4;
                p = (const unsigned char *)(base + phdr[i].p_vaddr);
+               if (!may_access(p))
+                       continue;
                rem = phdr[i].p_filesz;
                off = 0;
                while (rem - off >= sizeof(ElfW(Nhdr))) {
@@ -1057,13 +1074,18 @@ static int phdr_cb(struct dl_phdr_info *info, size_t size, void *data)
        const char *path = NULL, *name = info->dlpi_name;
        struct sym_obj *obj;
        unsigned int before;
-       int is_exe = 0;
+       int is_exe = !b->seen_exe;
        int idx, seen = 0, ret = 0;
 
+       /* The main executable is always the first object reported, but not
+        * every loader gives it an empty name (NetBSD passes the path the
+        * program was started with).
+        */
+       b->seen_exe = 1;
+
        if (!name || !*name) {
                /* the main executable has an empty name */
                path = name = get_exec_path();
-               is_exe = 1;
        }
        else if (strchr(name, '/')) {
                path = name;
@@ -1130,6 +1152,8 @@ static int phdr_cb(struct dl_phdr_info *info, size_t size, void *data)
                    info->dlpi_phdr[idx].p_filesz < sizeof(sym_xz_magic))
                        continue;
                p = (const unsigned char *)(info->dlpi_addr + info->dlpi_phdr[idx].p_vaddr);
+               if (!may_access(p))
+                       continue;
                if (memcmp(p, sym_xz_magic, sizeof(sym_xz_magic)) == 0) {
                        b->debugdata = p;
                        b->debugdata_size = info->dlpi_phdr[idx].p_filesz;