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#include "io.h"
#include <stdio.h>
#include <err.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
static size_t
mem_io_ptrace_do(const struct mem_io *io, void *ptr, const size_t offset, const size_t size, size_t (*iofun)(void*, size_t, size_t, FILE*))
{
if (fseek(io->backing, offset, SEEK_SET) != 0) {
warn("fseek(/proc/%u/mem, %zu)", io->pid, offset);
return 0;
}
return iofun(ptr, 1, size, io->backing);
}
static size_t
mem_io_ptrace_write(const struct mem_io *io, const void *ptr, const size_t offset, const size_t size)
{
clearerr(io->backing);
const size_t ret = mem_io_ptrace_do(io, (void*)ptr, offset, size, (size_t(*)())fwrite);
if (ferror(io->backing))
warn("fwrite(/proc/%u/mem)", io->pid);
return ret;
}
static size_t
mem_io_ptrace_read(const struct mem_io *io, void *ptr, const size_t offset, const size_t size)
{
clearerr(io->backing);
const size_t ret = mem_io_ptrace_do(io, ptr, offset, size, fread);
if (ferror(io->backing))
warn("fread(/proc/%u/mem)", io->pid);
return ret;
}
static void
mem_io_ptrace_cleanup(struct mem_io *io)
{
if (io->backing)
fclose(io->backing);
if (io->pid)
ptrace(PTRACE_DETACH, io->pid, 1, 0);
}
bool
mem_io_ptrace_init(struct mem_io *io, const pid_t pid)
{
*io = (struct mem_io){
.pid = pid,
.read = mem_io_ptrace_read,
.write = mem_io_ptrace_write,
.cleanup = mem_io_ptrace_cleanup
};
if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) == -1L) {
warn("ptrace(PTRACE_ATTACH, %u, NULL, NULL)", pid);
goto fail;
}
{
int status;
if (waitpid(pid, &status, 0) == -1 || !WIFSTOPPED(status)) {
warn("waitpid(%u) == %d", pid, status);
goto fail;
}
}
char path[128];
snprintf(path, sizeof(path), "/proc/%u/mem", pid);
if (!(io->backing = fopen(path, "w+b"))) {
warn("fopen(%s)", path);
goto fail;
}
return true;
fail:
io->cleanup(io);
return false;
}
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