On Tue, Jan 19, 2016 at 9:50 AM, Peter Maydell <peter.mayd...@linaro.org> wrote:
> On 18 January 2016 at 07:12, Peter Crosthwaite
> <crosthwaitepe...@gmail.com> wrote:
>> Add an API to load an elf header header from a file. Populates a
>> buffer with the header contents, as well as a boolean for whether the
>> elf is 64b or not. Both arguments are optional.
>>
>> Signed-off-by: Peter Crosthwaite <crosthwaite.pe...@gmail.com>
>> ---
>>
>> hw/core/loader.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>> include/hw/loader.h | 1 +
>> 2 files changed, 49 insertions(+)
>>
>> diff --git a/hw/core/loader.c b/hw/core/loader.c
>> index 6b69852..28da8e2 100644
>> --- a/hw/core/loader.c
>> +++ b/hw/core/loader.c
>> @@ -331,6 +331,54 @@ const char *load_elf_strerror(int error)
>> }
>> }
>>
>> +void load_elf_hdr(const char *filename, void *hdr, bool *is64, Error **errp)
>> +{
>> + int fd;
>> + uint8_t e_ident[EI_NIDENT];
>> + size_t hdr_size, off = 0;
>> + bool is64l;
>> +
>> + fd = open(filename, O_RDONLY | O_BINARY);
>> + if (fd < 0) {
>> + error_setg_errno(errp, errno, "Fail to open file");
>
> "Failed" (also below).
>
Fixed (x2).
> I don't think we end up with the filename anywhere in the
> error message; it would be helpful if we could include it.
>
Fixed (x4)
>> + return;
>> + }
>> + if (read(fd, e_ident, sizeof(e_ident)) != sizeof(e_ident)) {
>> + error_setg_errno(errp, errno, "Fail to read file");
>> + goto fail;
>> + }
>> + if (e_ident[0] != ELFMAG0 ||
>> + e_ident[1] != ELFMAG1 ||
>> + e_ident[2] != ELFMAG2 ||
>> + e_ident[3] != ELFMAG3) {
>> + error_setg(errp, "Bad ELF magic");
>> + goto fail;
>> + }
>> +
>> + is64l = e_ident[EI_CLASS] == ELFCLASS64;
>> + hdr_size = is64l ? sizeof(Elf64_Ehdr) : sizeof(Elf32_Ehdr);
>> + if (is64) {
>> + *is64 = is64l;
>> + }
>> +
>> + lseek(fd, 0, SEEK_SET);
>
> You're not checking this lseek for failure (and you don't
> need it anyway, because you could just copy the magic bytes
> into *hdr and read four fewer bytes).
>
OK, so I have optimised it away. What I am doing now is always reading
to straight to hdr[], and if the caller passes hdr == NULL, then hdr
is set to a local buffer (and the full header read is still skipped as
per current logic).
>> + while (hdr && off < hdr_size) {
>> + size_t br = read(fd, hdr + off, hdr_size - off);
>> + switch (br) {
>> + case 0:
>> + error_setg(errp, "File too short");
>> + goto fail;
>> + case -1:
>> + error_setg_errno(errp, errno, "Failed to read file");
>> + goto fail;
>> + }
>> + off += br;
>> + }
>> +
>> +fail:
>> + close(fd);
>> +}
>> +
>> /* return < 0 if error, otherwise the number of bytes loaded in memory */
>> int load_elf(const char *filename, uint64_t (*translate_fn)(void *,
>> uint64_t),
>> void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
>> diff --git a/include/hw/loader.h b/include/hw/loader.h
>> index f7b43ab..33067f8 100644
>> --- a/include/hw/loader.h
>> +++ b/include/hw/loader.h
>> @@ -36,6 +36,7 @@ int load_elf(const char *filename, uint64_t
>> (*translate_fn)(void *, uint64_t),
>> void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
>> uint64_t *highaddr, int big_endian, int elf_machine,
>> int clear_lsb);
>> +void load_elf_hdr(const char *filename, void *hdr, bool *is64, Error
>> **errp);
>
> Doc comment, please.
>
Added:
+
+/** load_elf_hdr:
+ * @filename: Path of ELF file
+ * @hdr: Buffer to populate with header data. Header data will not be
+ * filled if set to NULL.
+ * @is64: Set to true if the ELF is 64bit. Ignored if set to NULL
+ * @errp: Populated with an error in failure cases
+ *
+ * Inspect as ELF file's header. Read its full header contents into a
+ * buffer and/or determine if the ELF is 64bit.
+ */
Regards,
Peter
>> int load_aout(const char *filename, hwaddr addr, int max_sz,
>> int bswap_needed, hwaddr target_page_size);
>> int load_uimage(const char *filename, hwaddr *ep,
>> --
>> 1.9.1
>
> thanks
> -- PMM
