《APUE》：遞歸遍歷目錄層次結構，並按文件類型計數

《Unix環境高級編程》這本書附帶了許多短小精美的小程序，我在閱讀此書的時候，將書上的代碼按照自己的理解重寫了一遍（大部分是抄書上的），加深一下自己的理解（純看書太困了，呵呵）。此例子在Ubuntu 10.04上測試通過。

相關鏈接

• 《UNIX環境高級編程》（第二版）apue.h的錯誤 http://www.linuxidc.com/Linux/2011-04/34662.htm
• Unix環境高級編程 源代碼地址 http://www.linuxidc.com/Linux/2011-04/34826.htm

1. //《APUE》程序4－7：
2. //遞歸遍歷目錄層次結構，並按文件類型計數
3. #include <unistd.h>
4. #include <utime.h>
5. #include <dirent.h>
6. #include <sys/stat.h>
7. #include <stdio.h>
8. #include <limits.h>
9. #include <stdlib.h>
10. #include <string.h>
12. typedef int Myfunc(const char*, const struct stat*, int);
13. static Myfunc myfunc;
14. static int myftw(char*, Myfunc*);
15. static int dopath(Myfunc*);
16. static long nreg, ndir, nblk, nchr, nfifo, nslink, nsock, ntot;
18. int main(int argc, char **argv)
19. {
20. int ret;
21. if( argc != 2 )
22. {
23. fprintf(stderr, "Usage: ftw <starting-pathname>\n");
24. exit(1);
25. }
26. ret = myftw(argv[1], myfunc);
27. ntot = nreg + ndir + nblk + nchr + nfifo + nslink + nsock;
28. //
29. if( 0 == ntot )
30. ntot = 1;
32. //輸入各種文件的數量及所占的比例
33. printf("reglar files = %7ld, %5.2lf %% \n",
34. nreg, nreg*100.0/ntot);
35. printf("directories = %7ld, %5.2lf %% \n",
36. ndir, ndir*100.0/ntot);
37. printf("block special = %7ld, %5.2lf %% \n",
38. nblk, nblk*100.0/ntot);
39. printf("char special = %7ld, %5.2lf %% \n",
40. nchr, nchr*100.0/ntot);
41. printf("FIFOs = %7ld, %5.2lf %% \n",
42. nfifo, nfifo*100.0/ntot);
43. printf("symbolic links = %7ld, %5.2lf %% \n",
44. nslink, nslink*100.0/ntot);
45. printf("sockets = %7ld, %5.2lf %% \n",
46. nsock, nsock*100.0/ntot);
47. return ret;
48. }
50. #define FTW_F 1
51. #define FTW_D 2
52. #define FTW_DNR 3
53. #define FTW_NS 4
55. static char *fullpath;
57. static int myftw(char *pathname, Myfunc *func)
58. {
59. //《APUE》書中，這個功能用了一個很復雜的函數path_alloc()來實現
60. //這裡我為了簡單起見，直接為它分配了一段內存完事
61. #ifdef PATH_MAX
62. const int PATH_LEN = PATH_MAX;
63. #else
64. const int PATH_LEN = 1024;
65. #endif
67. fullpath = malloc(PATH_LEN);
68. strncpy(fullpath, pathname, PATH_LEN);
69. fullpath[PATH_LEN-1] = '\0';
70. int res = dopath(func);
71. //《APUE》書中，好像沒有釋放這段內存
72. free(fullpath);
73. return res;
74. }
76. static int dopath(Myfunc* func)
77. {
78. struct stat statbuf;
79. struct dirent *dirp;
80. DIR *dp;
81. int ret;
82. char *ptr;
84. int temp;
85. temp = lstat(fullpath, &statbuf);
86. //文件狀態錯誤
87. if( temp < 0 )
88. return func(fullpath, &statbuf, FTW_NS);
89. temp = S_ISDIR(statbuf.st_mode);
90. //不是文件夾
91. if( 0 == temp )
92. return func(fullpath, &statbuf, FTW_F);
94. ret = func(fullpath, &statbuf, FTW_D);
95. if( ret != 0 )
96. return ret;
97. ptr = fullpath + strlen(fullpath);
98. *ptr++ = '/';
99. *ptr = 0;
101. dp = opendir(fullpath);
102. //不能讀取該文件夾
103. if( NULL == dp )
104. return func(fullpath, &statbuf, FTW_DNR);
106. while( (dirp = readdir(dp)) != NULL )
107. {
108. //忽略.和..這兩個文件夾
109. if( strcmp(dirp->d_name, ".") == 0 ||
110. strcmp(dirp->d_name, "..") == 0 )
111. continue;
112. strcpy(ptr, dirp->d_name);
113. //遞歸遍歷各個子文件夾
114. ret = dopath(func);
115. if( ret != 0 )
116. break;
117. }
119. ptr[-1] = 0;
120. if( closedir(dp) < 0 )
121. {
122. fprintf(stderr, "can't close directory %s\n", fullpath);
123. }
124. return ret;
125. }
127. static int myfunc(const char *pathname, const struct stat *statptr, int type)
128. {
129. switch(type)
130. {
131. case FTW_F:
132. switch( statptr->st_mode & S_IFMT )
133. {
134. case S_IFREG:
135. nreg++;
136. printf("reg: %s\n", fullpath);
137. break;
138. case S_IFBLK:
139. nblk++;
140. printf("blk: %s\n", fullpath);
141. break;
142. case S_IFCHR:
143. nchr++;
144. printf("chr: %s\n", fullpath);
145. break;
146. case S_IFIFO:
147. nfifo++;
148. printf("fifo: %s\n", fullpath);
149. break;
150. case S_IFLNK:
151. nslink++;
152. printf("slink: %s\n", fullpath);
153. break;
154. case S_IFSOCK:
155. nsock++;
156. printf("socket: %s\n", fullpath);
157. break;
158. case S_IFDIR:
159. fprintf(stderr, "For S_IFDIR for %s\n", pathname);
160. exit(1);
161. }
162. //《APUE》書中沒有輸出遍歷的結果，這個是我自己加上去的
163. break;
164. case FTW_D:
165. ndir++;
166. printf("DIR: %s\n", fullpath);
167. break;
168. case FTW_DNR:
169. fprintf(stderr, "can't read directory %s\n", pathname);
170. break;
171. case FTW_NS:
172. fprintf(stderr, "stat error for %s\n", pathname);
173. break;
174. default:
175. fprintf(stderr, "unkown type %d for pathname %s\n",
176. type, pathname);
177. }
178. return 0;
179. }

運行示例（加下劃線的為輸入）：

www.linuxidc.com @ubuntu:~/code$ gcc temp.c -o temp

www.linuxidc.com @ubuntu:~/code$ ./temp /etc

DIR: /etc
DIR: /etc/sudoers.d
reg: /etc/sudoers.d/README

...............

reglar files = 1593, 59.89 %
directories = 306, 11.50 %
block special = 0, 0.00 %
char special = 0, 0.00 %
FIFOs = 0, 0.00 %
symbolic links = 761, 28.61 %
sockets = 0, 0.00 %