/*
 * link.h — dynamic-linker introspection (dl_iterate_phdr).
 *
 * Non-POSIX (glibc/BSD extension). The implementation of dl_iterate_phdr lives
 * in relibc's dynamic linker (src/header/link/mod.rs); this header only
 * declares the ABI. Keep `struct dl_phdr_info` in sync with the Rust
 * `DlPhdrInfo` struct in that module.
 */
#ifndef _RELIBC_LINK_H
#define _RELIBC_LINK_H

#include <elf.h>
#include <stddef.h>

/*
 * glibc-compatible `ElfW(type)` macro: expands to the native-word-size ELF type
 * (Elf64_type on LP64, Elf32_type otherwise). Portable ELF code (Mesa's
 * util/build_id.c, unwinders) uses `ElfW(Nhdr)` etc. and expects <link.h> to
 * provide this.
 */
#ifndef ElfW
# if defined(__LP64__) || defined(_LP64) || (__SIZEOF_POINTER__ == 8)
#  define ElfW(type) Elf64_##type
# else
#  define ElfW(type) Elf32_##type
# endif
#endif

#ifdef __cplusplus
extern "C" {
#endif

struct dl_phdr_info {
    Elf64_Addr         dlpi_addr;      /* base / load bias of the object      */
    const char        *dlpi_name;      /* object pathname (NUL-terminated)    */
    const Elf64_Phdr  *dlpi_phdr;      /* pointer to the program header array */
    Elf64_Half         dlpi_phnum;     /* number of program headers           */
    /* glibc-compatible extension fields */
    unsigned long long dlpi_adds;      /* # objects added since process start */
    unsigned long long dlpi_subs;      /* # objects removed since start       */
    size_t             dlpi_tls_modid; /* TLS module ID (0 if none)           */
    void              *dlpi_tls_data;  /* TLS block for the calling thread    */
};

/*
 * Call `callback` once per loaded object. `size` is sizeof(struct dl_phdr_info).
 * Iteration stops as soon as a callback returns non-zero, and that value is
 * returned; otherwise the return value is that of the last callback (or 0 when
 * there are no objects).
 */
int dl_iterate_phdr(int (*callback)(struct dl_phdr_info *info,
                                    size_t size, void *data),
                    void *data);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* _RELIBC_LINK_H */