I Wanna know the Internal Members of struct FILE, the latest ones

Question

When I read pg.176 of The C programming Language by K&R, I was very excited. I found all the members of struct FILE ( which I was searching for ) and its just awesome to

Answer 1

Answer of the @unwind is good, but I found another one workaround for the Unix-like systems with the GCC.

Unfortunately, the C has not support for the reflection (Reflection support in C), but you may can parse a output the C preprocessor.

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Source code of shell script

setivolkylany$~/Downloads$ cat script.sh 

# a tempfile for source code on the C programming language
FILE_C=`tempfile`

# a tempfile for preprocessor`s output
FILE_I=`tempfile`

printf "#include \"stdio.h\"\nint main() {return 0;}" > $FILE_C
cpp $FILE_C > $FILE_I

# parse content of the tempfile for preprocessor`s output
# and display only the structure
print_it=false
while read line; do
    if [ "$line" == "struct _IO_FILE {" ]; then
        print_it=true
    fi;
    if [ "$print_it" = true ]; then
        echo $line
    fi;
    if [ "$line" == "};" ]; then
        print_it=false
    fi;
done < $FILE_I

# clean tempfiles
rm $FILE_C $FILE_I

Output

setivolkylany$~/Downloads$ ./script.sh 
struct _IO_FILE {
int _flags;




char* _IO_read_ptr;
char* _IO_read_end;
char* _IO_read_base;
char* _IO_write_base;
char* _IO_write_ptr;
char* _IO_write_end;
char* _IO_buf_base;
char* _IO_buf_end;

char *_IO_save_base;
char *_IO_backup_base;
char *_IO_save_end;

struct _IO_marker *_markers;

struct _IO_FILE *_chain;

int _fileno;



int _flags2;

__off_t _old_offset;



unsigned short _cur_column;
signed char _vtable_offset;
char _shortbuf[1];



_IO_lock_t *_lock;
# 293 "/usr/include/libio.h" 3 4
__off64_t _offset;
# 302 "/usr/include/libio.h" 3 4
void *__pad1;
void *__pad2;
void *__pad3;
void *__pad4;
size_t __pad5;

int _mode;

char _unused2[15 chrome-remote-desktop_current_amd64.deb data_structures_algorithms_tutorial.pdf dict-uk_ua-3-5-1.oxt getline.c jquery-3.1.1.min.js ld-linux.so (1).2 ld-linux.so.2 Makefile Portable Microsoft Office 2003.exe Python-3.5.2 script.sh teamviewer_12.0.71510_amd64.deb teamviewer_12.0.71510_i386.deb text_editor.zip sizeof (int) - 4 chrome-remote-desktop_current_amd64.deb data_structures_algorithms_tutorial.pdf dict-uk_ua-3-5-1.oxt getline.c jquery-3.1.1.min.js ld-linux.so (1).2 ld-linux.so.2 Makefile Portable Microsoft Office 2003.exe Python-3.5.2 script.sh teamviewer_12.0.71510_amd64.deb teamviewer_12.0.71510_i386.deb text_editor.zip sizeof (void *) - sizeof (size_t)];

};

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This decision is no very delicate, but rather an attempt implementation reflection in the C programming language.