[英]Read files in a directory using readdir_r and sort using qsort
I am trying to write a program in C that reads files from a directory and detects the name, user, group, and size of each file. 我试图用C编写一个程序,该程序从目录中读取文件并检测每个文件的名称,用户,组和大小。 The information for each file is stored in a struct array and sorted by file name using qsort.
每个文件的信息都存储在struct数组中,并使用qsort按文件名排序。 The sorted files are then printed to the screen.
然后将排序后的文件打印到屏幕上。 This program must use readdir_r, getpwuid_r and getgrgid_r.
该程序必须使用readdir_r,getpwuid_r和getgrgid_r。 I do not understand how the multiple arguments that must be supplied for the "_r" versions of these functions must be implemented to achieve my goal.
我不明白必须如何实现必须为这些功能的“ _r”版本提供的多个参数。 I am also receiving several "request for member 'name' in something not a structure or union" errors (also occur for 'size','user' and 'group').
我还收到一些“在非结构或联合的情况下要求成员'名称'”错误(“大小”,“用户”和“组”也发生)。
Can anyone help me understand how I can utilize the "_r" functions properly in this situation? 谁能帮助我了解在这种情况下如何正确使用“ _r”功能? The man pages were not clear enough for me to understand.
手册页不够清晰,我无法理解。
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <stddef.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
int main(int argc, char* argv[])
{
DIR *mydir;
struct dirent *myfile;
struct stat mystat;
struct passwd *pwd;
struct group *grp;
struct dirent *result;
struct entry
{
char *name;
char *user;
char *group;
int size;
};
struct entry entries[1024];
if(argc != 2)
{
perror("must supply a directory");
return -1;
}
mydir = opendir(argv[1]);
if(mydir==NULL)
{
perror("Cannot find directory");
return -1;
}
char buf[1024];
while((myfile = readdir_r(mydir, myfile, )) != NULL)
{
entries.name = myfile->d_name;
stat(buf, &mystat);
entries.size = mystat.st_size;
/* store owner's name in struct if it is found using getpwuid_r(). */
if ((pwd = getpwuid_r(mystat.st_uid, , , , ,)) != NULL)
entries.user = pwd->pw_name;
else
perror("user not found");
/* store group name in struct if it is found using getgrgid_r(). */
if ((grp = getgrgid_r(mystat.st_gid, , , , ,)) != NULL)
entries.group = grp->gr_name;
else
perror("group not found");
}
int cmpfunc( const void *a, const void *b)
{
char const *aa = (char const *)a;
char const *bb = (char const *)b;
return strcmp(aa, bb);
}
qsort(entries, 4, sizeof(int), cmpfunc);
int i = 0;
for(int i; i < sizeOf(entries); i++)
{
printf("%s %s %llu %s\n", entries.user, entries.group,
entries.size, entries.name);
}
closedir(mydir);
return 0;
}
Here is an example of using readdir_r()
... you should be able to figure out the others based upon this example: 这是使用
readdir_r()
的示例...您应该能够根据此示例找出其他示例:
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <string.h>
int main(int argc, char *argv[])
{
DIR *mydir;
struct dirent myfile;
struct dirent *result;
int rc;
if (argc != 2) {
perror("must supply a directory");
return -1;
}
mydir = opendir(argv[1]);
if (mydir == NULL) {
perror("Cannot find directory");
return -1;
}
while ((rc = readdir_r(mydir, &myfile, &result)) == 0 && result != NULL ) {
printf("myfile.entryName: -->%s<-- result->d_name: -->%s<--\n",
myfile.d_name,
result->d_name);
}
closedir(mydir);
}
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