elf32.c

/*
 * Copyright (c) 1999-2004 University of New South Wales
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include "elf.h"

int elf32_checkFile(
struct Elf32_Header const *file)
{
    if (file->e_ident[EI_MAG0] != ELFMAG0
        || file->e_ident[EI_MAG1] != ELFMAG1
        || file->e_ident[EI_MAG2] != ELFMAG2
        || file->e_ident[EI_MAG3] != ELFMAG3) {
        return -1; /* not an elf file */
    }
    if (file->e_ident[EI_CLASS] != ELFCLASS32) {
        return -2; /* not 32-bit file */
    }
    return 0; /* elf file looks OK */
}

/*
 * Returns the number of program segments in this elf file.
 */
unsigned int elf32_getNumSections(
    struct Elf32_Header const *elfFile)
{
    return elfFile->e_shnum;
}

char const *elf32_getStringTable(
    struct Elf32_Header const *elfFile)
{
    struct Elf32_Shdr const *sections = elf32_getSectionTable(elfFile);
    return (char const *)elfFile + sections[elfFile->e_shstrndx].sh_offset;
}

/* Returns a pointer to the program segment table, which is an array of
 * ELF32_Phdr_t structs.  The size of the array can be found by calling
 * getNumProgramSegments. */
struct Elf32_Phdr const *elf32_getProgramSegmentTable(
    struct Elf32_Header const *elfFile)
{
    struct Elf32_Header const *fileHdr = elfFile;
    return (struct Elf32_Phdr const *)(fileHdr->e_phoff + (long) elfFile);
}

/* Returns the number of program segments in this elf file. */
uint16_t elf32_getNumProgramHeaders(
    struct Elf32_Header const *elfFile)
{
    struct Elf32_Header const *fileHdr = elfFile;
    return fileHdr->e_phnum;
}

char const *elf32_getSectionName(
    struct Elf32_Header const *elfFile,
    unsigned int i)
{
    struct Elf32_Shdr const *sections = elf32_getSectionTable(elfFile);
    char const *str_table = elf32_getSegmentStringTable(elfFile);
    if (str_table == NULL) {
        return "<corrupted>";
    } else {
        return str_table + sections[i].sh_name;
    }
}

uint32_t elf32_getSectionSize(
    struct Elf32_Header const *elfFile,
    unsigned int i)
{
    struct Elf32_Shdr const *sections = elf32_getSectionTable(elfFile);
    return sections[i].sh_size;
}

uint32_t elf32_getSectionAddr(
    struct Elf32_Header const *elfFile,
    unsigned int i)
{
    struct Elf32_Shdr const *sections = elf32_getSectionTable(elfFile);
    return sections[i].sh_addr;
}

void const *elf32_getSection(
    struct Elf32_Header const *elfFile,
    unsigned int i)
{
    struct Elf32_Shdr const *sections = elf32_getSectionTable(elfFile);
    return (char *)elfFile + sections[i].sh_offset;
}

void const *elf32_getSectionNamed(
    struct Elf32_Header const *elfFile,
    char const *str)
{
    unsigned int numSections = elf32_getNumSections(elfFile);
    for (unsigned int i = 0; i < numSections; i++) {
        if (strcmp(str, elf32_getSectionName(elfFile, i)) == 0) {
            return elf32_getSection(elfFile, i);
        }
    }
    return NULL;
}

char const *elf32_getSegmentStringTable(
    struct Elf32_Header const *elfFile)
{
    struct Elf32_Header const *fileHdr = (struct Elf32_Header *) elfFile;
    if (fileHdr->e_shstrndx == 0) {
        return NULL;
    } else {
        return elf32_getStringTable(elfFile);
    }
}

#ifdef ELF_DEBUG
void elf32_printStringTable(
    struct Elf32_Header const *elfFile)
{
    struct Elf32_Shdr *sections = elf32_getSectionTable(elfFile);
    char *stringTable;

    if (!sections) {
        printf("No sections.\n");
        return;
    }

    stringTable = ((void *)elfFile) + sections[elfFile->e_shstrndx].sh_offset;

    printf("File is %p; sections is %p; string table is %p\n", elfFile, sections, stringTable);

    for (unsigned int counter = 0; counter < sections[elfFile->e_shstrndx].sh_size; counter++) {
        printf("%02x %c ", stringTable[counter],
               stringTable[counter] >= 0x20 ? stringTable[counter] : '.');
    }
}
#endif

uint32_t elf32_getSegmentType(
    struct Elf32_Header const *elfFile,
    unsigned int segment)
{
    return elf32_getProgramSegmentTable(elfFile)[segment].p_type;
}

void elf32_getSegmentInfo(
    struct Elf32_Header const *elfFile,
    unsigned int segment,
    uint64_t *p_vaddr,
    uint64_t *p_addr,
    uint64_t *p_filesz,
    uint64_t *p_offset,
    uint64_t *p_memsz)
{
    struct Elf32_Phdr const *segments = elf32_getProgramSegmentTable(elfFile);
    *p_addr = segments[segment].p_paddr;
    *p_vaddr = segments[segment].p_vaddr;
    *p_filesz = segments[segment].p_filesz;
    *p_offset = segments[segment].p_offset;
    *p_memsz = segments[segment].p_memsz;
}

uint32_t elf32_getEntryPoint(
    struct Elf32_Header const *elfFile)
{
    return elfFile->e_entry;
}