libkmod: Simplify section name handling

The name of string section is not needed, so it does not have to stored.
If section name is needed, return a char pointer instead of forcing the
caller to handle offset and memory calculations.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/196
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>

diff --git a/libkmod/libkmod-elf.c b/libkmod/libkmod-elf.c
index 49b709574200087ba0bf5b6ada6caf7548d56b0f..ade39c29112e186f3ed3a59f30a8ddb2458506e4 100644 (file)
--- a/libkmod/libkmod-elf.c
+++ b/libkmod/libkmod-elf.c
@@ -42,7 +42,6 @@ struct kmod_elf {
                        uint16_t section; /* index of the strings section */
                        uint64_t size;
                        uint64_t offset;
-                       uint32_t nameoff; /* offset in strings itself */
                } strings;
                uint16_t machine;
        } header;
@@ -198,8 +197,9 @@ static inline uint64_t elf_get_section_header_offset(const struct kmod_elf *elf,
 
 static inline int elf_get_section_info(const struct kmod_elf *elf, uint16_t idx,
                                       uint64_t *offset, uint64_t *size,
-                                      uint32_t *nameoff)
+                                      const char **name)
 {
+       uint64_t nameoff;
        uint64_t off = elf_get_section_header_offset(elf, idx);
 
        if (off == 0) {
@@ -216,30 +216,33 @@ static inline int elf_get_section_info(const struct kmod_elf *elf, uint16_t idx,
                        goto fail;
                *size = READV(sh_size);
                *offset = READV(sh_offset);
-               *nameoff = READV(sh_name);
+               nameoff = READV(sh_name);
        } else {
                Elf64_Shdr *hdr;
                if (!elf_range_valid(elf, off, sizeof(*hdr)))
                        goto fail;
                *size = READV(sh_size);
                *offset = READV(sh_offset);
-               *nameoff = READV(sh_name);
+               nameoff = READV(sh_name);
        }
 #undef READV
 
        if (!elf_range_valid(elf, *offset, *size))
                goto fail;
 
+       if (nameoff >= elf->header.strings.size)
+               goto fail;
+       *name = elf_get_mem(elf, elf->header.strings.offset + nameoff);
+
        ELFDBG(elf,
-              "section=%" PRIu16 " is: offset=%" PRIu64 " size=%" PRIu64
-              " nameoff=%" PRIu32 "\n",
-              idx, *offset, *size, *nameoff);
+              "section=%" PRIu16 " is: offset=%" PRIu64 " size=%" PRIu64 " name=%s\n",
+              idx, *offset, *size, *name);
 
        return 0;
 fail:
        *offset = 0;
        *size = 0;
-       *nameoff = 0;
+       *name = NULL;
        return -EINVAL;
 }
 
@@ -255,6 +258,7 @@ struct kmod_elf *kmod_elf_new(const void *memory, off_t size)
        uint64_t min_size;
        size_t shdrs_size, shdr_size;
        int err;
+       const char *name;
 
        assert_cc(sizeof(uint16_t) == sizeof(Elf32_Half));
        assert_cc(sizeof(uint16_t) == sizeof(Elf64_Half));
@@ -325,7 +329,7 @@ struct kmod_elf *kmod_elf_new(const void *memory, off_t size)
 
        if (elf_get_section_info(elf, elf->header.strings.section,
                                 &elf->header.strings.offset, &elf->header.strings.size,
-                                &elf->header.strings.nameoff) < 0) {
+                                &name) < 0) {
                ELFDBG(elf, "could not get strings section\n");
                goto invalid;
        } else {
@@ -357,20 +361,14 @@ const void *kmod_elf_get_memory(const struct kmod_elf *elf)
 
 static int elf_find_section(const struct kmod_elf *elf, const char *section)
 {
-       uint64_t nameslen;
-       const char *names = elf_get_strings_section(elf, &nameslen);
        uint16_t i;
 
        for (i = 1; i < elf->header.section.count; i++) {
                uint64_t off, size;
-               uint32_t nameoff;
                const char *n;
-               int err = elf_get_section_info(elf, i, &off, &size, &nameoff);
+               int err = elf_get_section_info(elf, i, &off, &size, &n);
                if (err < 0)
                        continue;
-               if (nameoff >= nameslen)
-                       continue;
-               n = names + nameoff;
                if (!streq(section, n))
                        continue;
 
@@ -384,8 +382,6 @@ static int elf_find_section(const struct kmod_elf *elf, const char *section)
 int kmod_elf_get_section(const struct kmod_elf *elf, const char *section,
                         uint64_t *sec_off, uint64_t *sec_size)
 {
-       uint64_t nameslen;
-       const char *names = elf_get_strings_section(elf, &nameslen);
        uint16_t i;
 
        *sec_off = 0;
@@ -393,14 +389,10 @@ int kmod_elf_get_section(const struct kmod_elf *elf, const char *section,
 
        for (i = 1; i < elf->header.section.count; i++) {
                uint64_t off, size;
-               uint32_t nameoff;
                const char *n;
-               int err = elf_get_section_info(elf, i, &off, &size, &nameoff);
+               int err = elf_get_section_info(elf, i, &off, &size, &n);
                if (err < 0)
                        continue;
-               if (nameoff >= nameslen)
-                       continue;
-               n = names + nameoff;
                if (!streq(section, n))
                        continue;
 
@@ -767,12 +759,12 @@ static uint64_t kmod_elf_resolve_crc(const struct kmod_elf *elf, uint64_t crc,
 {
        int err;
        uint64_t off, size;
-       uint32_t nameoff;
+       const char *name;
 
        if (shndx == SHN_ABS || shndx == SHN_UNDEF)
                return crc;
 
-       err = elf_get_section_info(elf, shndx, &off, &size, &nameoff);
+       err = elf_get_section_info(elf, shndx, &off, &size, &name);
        if (err < 0) {
                ELFDBG(elf, "Could not find section index %" PRIu16 " for crc", shndx);
                return (uint64_t)-1;