Usando strace para um arquivo C

Question

Eu tenho um arquivo C que quero rastrear o que está acontecendo. Estou tentando usar:

strace -o trace.txt random.c

Mas diz que:

strace: Can't stat 'random.c': No such file or directory

Eu estive procurando por strace pela última hora agora, e não sei exatamente o que estou fazendo de errado. Existe um comando mais fácil para rastrear o que é compilado / executado? O 'strace' só funciona em arquivos shell?

    

Answer 1

Como o thrig diz , você deve compilar seu programa em C ( usando um compilador como gcc ou clang ), use strace para executar o binário compilado.

ek@Io:~$ cat >hello.c <<'EOF'
> #include <stdio.h>
>
> int main(void)
> {
>     puts("Hello, world!");
>     return 0;
> }
> EOF
ek@Io:~$ gcc -ansi -pedantic -Wall -Wextra -g -o hello hello.c
ek@Io:~$ strace ./hello
execve("./hello", ["./hello"], [/* 19 vars */]) = 0
brk(NULL)                               = 0x220f000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8000316000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=156046, ...}) = 0
mmap(NULL, 156046, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f80002ef000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "7ELF
ek@Io:~$ strace hello.c
strace: Can't stat 'hello.c': No such file or directory
ek@Io:~$ strace ./hello.c
execve("./hello.c", ["./hello.c"], [/* 19 vars */]) = -1 EACCES (Permission denied)
write(2, "strace: exec: Permission denied\n", 32strace: exec: Permission denied
) = 32
exit_group(1)                           = ?
+++ exited with 1 +++
ek@Io:~$ chmod +x hello.c
ek@Io:~$ strace ./hello.c
execve("./hello.c", ["./hello.c"], [/* 19 vars */]) = -1 ENOEXEC (Exec format error)
write(2, "strace: exec: Exec format error\n", 32strace: exec: Exec format error
) = 32
exit_group(1)                           = ?
+++ exited with 1 +++
ek@Io:~$ cat >hello.c <<'EOF'
> #include <stdio.h>
>
> int main(void)
> {
>     puts("Hello, world!");
>     return 0;
> }
> EOF
ek@Io:~$ gcc -ansi -pedantic -Wall -Wextra -g -o hello hello.c
ek@Io:~$ strace ./hello
execve("./hello", ["./hello"], [/* 19 vars */]) = 0
brk(NULL)                               = 0x220f000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8000316000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=156046, ...}) = 0
mmap(NULL, 156046, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f80002ef000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "7ELF
ek@Io:~$ strace hello.c
strace: Can't stat 'hello.c': No such file or directory
ek@Io:~$ strace ./hello.c
execve("./hello.c", ["./hello.c"], [/* 19 vars */]) = -1 EACCES (Permission denied)
write(2, "strace: exec: Permission denied\n", 32strace: exec: Permission denied
) = 32
exit_group(1)                           = ?
+++ exited with 1 +++
ek@Io:~$ chmod +x hello.c
ek@Io:~$ strace ./hello.c
execve("./hello.c", ["./hello.c"], [/* 19 vars */]) = -1 ENOEXEC (Exec format error)
write(2, "strace: exec: Exec format error\n", 32strace: exec: Exec format error
) = 32
exit_group(1)                           = ?
+++ exited with 1 +++
%pre%%pre%%pre%%pre%%pre%%pre%%pre%>%pre%%pre%%pre%%pre%P\t%pre%%pre%%pre%%pre%%pre%"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1864888, ...}) = 0
mmap(NULL, 3967392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7fffd2a000
mprotect(0x7f7fffee9000, 2097152, PROT_NONE) = 0
mmap(0x7f80000e9000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bf000) = 0x7f80000e9000
mmap(0x7f80000ef000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f80000ef000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f80002ee000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f80002ed000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f80002ec000
arch_prctl(ARCH_SET_FS, 0x7f80002ed700) = 0
mprotect(0x7f80000e9000, 16384, PROT_READ) = 0
mprotect(0x600000, 4096, PROT_READ)     = 0
mprotect(0x7f8000318000, 4096, PROT_READ) = 0
munmap(0x7f80002ef000, 156046)          = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 2), ...}) = 0
brk(NULL)                               = 0x220f000
brk(0x2230000)                          = 0x2230000
write(1, "Hello, world!\n", 14Hello, world!
)         = 14
exit_group(0)                           = ?
+++ exited with 0 +++
%pre%%pre%%pre%%pre%%pre%%pre%>%pre%%pre%%pre%%pre%P\t%pre%%pre%%pre%%pre%%pre%"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1864888, ...}) = 0
mmap(NULL, 3967392, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7fffd2a000
mprotect(0x7f7fffee9000, 2097152, PROT_NONE) = 0
mmap(0x7f80000e9000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1bf000) = 0x7f80000e9000
mmap(0x7f80000ef000, 14752, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f80000ef000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f80002ee000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f80002ed000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f80002ec000
arch_prctl(ARCH_SET_FS, 0x7f80002ed700) = 0
mprotect(0x7f80000e9000, 16384, PROT_READ) = 0
mprotect(0x600000, 4096, PROT_READ)     = 0
mprotect(0x7f8000318000, 4096, PROT_READ) = 0
munmap(0x7f80002ef000, 156046)          = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 2), ...}) = 0
brk(NULL)                               = 0x220f000
brk(0x2230000)                          = 0x2230000
write(1, "Hello, world!\n", 14Hello, world!
)         = 14
exit_group(0)                           = ?
+++ exited with 0 +++

Você ainda pode usar as opções necessárias para strace , como -o .

strace não terá êxito na execução do código-fonte C. Mesmo se você der um caminho com um / para insistir que tente fazer isso, ele falhará:

%pre%

Mesmo que você tenha marcado o arquivo .c , ele ainda não poderá ser executado:

%pre% Em suma, você tem que compilar seu programa em C e executar o binário compilado em vez do próprio arquivo de código-fonte. Assim como você não pode executar um arquivo .c normalmente (ou seja, ./hello.c falha), você não pode executá-lo com strace .