问如何确定Git是将文件处理为二进制文件还是文本文件？

EN

package-lock.json binary

git check-attr --all package-lock.json 
package-lock.json: binary: set
package-lock.json: diff: unset
package-lock.json: merge: unset
package-lock.json: text: unset

git check-attr --all package.json

/***********************************************************
 * is_binary.c 
 *
 * Usage: is_binary <pathname>
 *   Returns a 1 if a binary; return a 0 if non-binary
 * 
 * Thanks to Git and Stackoverflow developers for helping with these routines:
 * - the buffer_is_binary() routine from the xdiff-interface.c module 
 *   in git source code.
 * - the read-a-filename-from-stdin route
 * - the read-a-file-into-memory (fill_buffer()) routine
 *
 * To build:
 *    % gcc is_binary.c -o is_binary
 *
 * To build debuggable (to push a few messages to stdout):
 *    % gcc -DDEBUG=1 ./is_binary.c -o is_binary
 *
 * BUGS:
 *  Doesn't work with piped input, like 
 *    % cat foo.tar | is_binary 
 *  Claims that zero input is binary. Actually, 
 *  what should it be?
 *
 * Revision 1.4
 *
 * Tue Sep 12 09:01:33 EDT 2017
***********************************************************/
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define MAX_PATH_LENGTH 200
#define FIRST_FEW_BYTES 8000

/* global, unfortunately */
char *source_blob_buffer;

/* From: https://stackoverflow.com/questions/14002954/c-programming-how-to-read-the-whole-file-contents-into-a-buffer */

/* From: https://stackoverflow.com/questions/1563882/reading-a-file-name-from-piped-command */

/* From: https://stackoverflow.com/questions/6119956/how-to-determine-if-git-handles-a-file-as-binary-or-as-text
*/

/* The key routine in this function is from libc: void *memchr(const void *s, int c, size_t n); */
/* Checks for any occurrence of a zero byte (NUL character) in the first 8000 bytes (or the entire length if shorter). */

int buffer_is_binary(const char *ptr, unsigned long size)
{
  if (FIRST_FEW_BYTES < size)
    size = FIRST_FEW_BYTES;
    /* printf("buff = %s.\n", ptr); */
  return !!memchr(ptr, 0, size);
}
int fill_buffer(FILE * file_object_pointer) {
  fseek(file_object_pointer, 0, SEEK_END);
  long fsize = ftell(file_object_pointer);
  fseek(file_object_pointer, 0, SEEK_SET);  //same as rewind(f);
  source_blob_buffer = malloc(fsize + 1);
  fread(source_blob_buffer, fsize, 1, file_object_pointer);
  fclose(file_object_pointer);
  source_blob_buffer[fsize] = 0;
  return (fsize + 1);
}
int main(int argc, char *argv[]) {

  char pathname[MAX_PATH_LENGTH];
  FILE *file_object_pointer;

  if (argc == 1) {
    file_object_pointer = stdin;
  } else {
    strcpy(pathname,argv[1]);
#ifdef DEBUG
    printf("pathname=%s.\n", pathname); 
#endif 
    file_object_pointer = fopen (pathname, "rb");
    if (file_object_pointer == NULL) {
      printf ("I'm sorry, Dave, I can't do that--");
      printf ("open the file '%s', that is.\n", pathname);
      exit(3);
    }
  }
  if (!file_object_pointer) {
    printf("Not a file nor a pipe--sorry.\n");
    exit (4);
  }
  int fsize = fill_buffer(file_object_pointer);
  int result = buffer_is_binary(source_blob_buffer, fsize - 2);

#ifdef DEBUG
  if (result == 1) {
    printf ("%s %d\n", pathname, fsize - 1);
  }
  else {
    printf ("File '%s' is NON-BINARY; size is %d bytes.\n", pathname, fsize - 1); 
  }
#endif
  exit(result);
  /* easy check -- 'echo $?' after running */
}

file --mime-encoding *