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1 | /* |
2 | * du.c: implementation of du.h. |
3 | */ |
4 | |
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5 | #include "agedu.h" |
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6 | #include "du.h" |
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7 | #include "alloc.h" |
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8 | |
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9 | #if !defined __linux__ || !defined O_NOATIME || defined HAVE_FDOPENDIR |
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10 | |
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11 | #ifdef HAVE_DIRENT_H |
12 | # include <dirent.h> |
13 | #endif |
14 | #ifdef HAVE_NDIR_H |
15 | # include <ndir.h> |
16 | #endif |
17 | #ifdef HAVE_SYS_DIR_H |
18 | # include <sys/dir.h> |
19 | #endif |
20 | #ifdef HAVE_SYS_NDIR_H |
21 | # include <sys/ndir.h> |
22 | #endif |
23 | |
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24 | /* |
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25 | * Wrappers around POSIX opendir, readdir and closedir, which |
26 | * permit me to replace them with different wrappers in special |
27 | * circumstances. |
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28 | */ |
29 | |
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30 | typedef DIR *dirhandle; |
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31 | |
32 | int open_dir(const char *path, dirhandle *dh) |
33 | { |
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34 | #if defined O_NOATIME && defined HAVE_FDOPENDIR |
35 | |
36 | /* |
37 | * On Linux, we have the O_NOATIME flag. This means we can |
38 | * read the contents of directories without affecting their |
39 | * atimes, which enables us to at least try to include them in |
40 | * the age display rather than exempting them. |
41 | * |
42 | * Unfortunately, opendir() doesn't let us open a directory |
43 | * with O_NOATIME. So instead, we have to open the directory |
44 | * with vanilla open(), and then use fdopendir() to translate |
45 | * the fd into a POSIX dir handle. |
46 | */ |
47 | int fd; |
48 | |
49 | fd = open(path, O_RDONLY | O_NONBLOCK | O_NOCTTY | O_LARGEFILE | |
50 | O_NOATIME | O_DIRECTORY); |
51 | if (fd < 0) { |
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52 | /* |
53 | * Opening a file with O_NOATIME is not unconditionally |
54 | * permitted by the Linux kernel. As far as I can tell, |
55 | * it's permitted only for files on which the user would |
56 | * have been able to call utime(2): in other words, files |
57 | * for which the user could have deliberately set the |
58 | * atime back to its original value after finishing with |
59 | * it. Hence, O_NOATIME has no security implications; it's |
60 | * simply a cleaner, faster and more race-condition-free |
61 | * alternative to stat(), a normal open(), and a utimes() |
62 | * when finished. |
63 | * |
64 | * The upshot of all of which, for these purposes, is that |
65 | * we must be prepared to try again without O_NOATIME if |
66 | * we receive EPERM. |
67 | */ |
68 | if (errno == EPERM) |
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69 | fd = open(path, O_RDONLY | O_NONBLOCK | O_NOCTTY | |
70 | O_LARGEFILE | O_DIRECTORY); |
71 | if (fd < 0) |
72 | return -1; |
73 | } |
74 | |
75 | *dh = fdopendir(fd); |
76 | #else |
77 | *dh = opendir(path); |
78 | #endif |
79 | |
80 | if (!*dh) |
81 | return -1; |
82 | return 0; |
83 | } |
84 | |
85 | const char *read_dir(dirhandle *dh) |
86 | { |
87 | struct dirent *de = readdir(*dh); |
88 | return de ? de->d_name : NULL; |
89 | } |
90 | |
91 | void close_dir(dirhandle *dh) |
92 | { |
93 | closedir(*dh); |
94 | } |
95 | |
96 | #else /* defined __linux__ && !defined HAVE_FDOPENDIR */ |
97 | |
98 | /* |
99 | * Earlier versions of glibc do not have fdopendir(). Therefore, |
100 | * if we are on Linux and still wish to make use of O_NOATIME, we |
101 | * have no option but to talk directly to the kernel system call |
102 | * interface which underlies the POSIX opendir/readdir machinery. |
103 | */ |
104 | |
105 | #define __KERNEL__ |
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106 | #include <linux/types.h> |
107 | #include <linux/dirent.h> |
108 | #include <linux/unistd.h> |
109 | |
110 | _syscall3(int, getdents, uint, fd, struct dirent *, dirp, uint, count) |
111 | |
112 | typedef struct { |
113 | int fd; |
114 | struct dirent data[32]; |
115 | struct dirent *curr; |
116 | int pos, endpos; |
117 | } dirhandle; |
118 | |
119 | int open_dir(const char *path, dirhandle *dh) |
120 | { |
121 | /* |
122 | * As above, we try with O_NOATIME and then fall back to |
123 | * trying without it. |
124 | */ |
125 | dh->fd = open(path, O_RDONLY | O_NONBLOCK | O_NOCTTY | O_LARGEFILE | |
126 | O_NOATIME | O_DIRECTORY); |
127 | if (dh->fd < 0) { |
128 | if (errno == EPERM) |
129 | dh->fd = open(path, O_RDONLY | O_NONBLOCK | O_NOCTTY | |
130 | O_LARGEFILE | O_DIRECTORY); |
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131 | if (dh->fd < 0) |
132 | return -1; |
133 | } |
134 | |
135 | dh->pos = dh->endpos = 0; |
136 | |
137 | return 0; |
138 | } |
139 | |
140 | const char *read_dir(dirhandle *dh) |
141 | { |
142 | const char *ret; |
143 | |
144 | if (dh->pos >= dh->endpos) { |
145 | dh->curr = dh->data; |
146 | dh->pos = 0; |
147 | dh->endpos = getdents(dh->fd, dh->data, sizeof(dh->data)); |
148 | if (dh->endpos <= 0) |
149 | return NULL; |
150 | } |
151 | |
152 | ret = dh->curr->d_name; |
153 | |
154 | dh->pos += dh->curr->d_reclen; |
155 | dh->curr = (struct dirent *)((char *)dh->data + dh->pos); |
156 | |
157 | return ret; |
158 | } |
159 | |
160 | void close_dir(dirhandle *dh) |
161 | { |
162 | close(dh->fd); |
163 | } |
164 | |
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165 | #endif /* !defined __linux__ || defined HAVE_FDOPENDIR */ |
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166 | |
167 | static int str_cmp(const void *av, const void *bv) |
168 | { |
169 | return strcmp(*(const char **)av, *(const char **)bv); |
170 | } |
171 | |
172 | static void du_recurse(char **path, size_t pathlen, size_t *pathsize, |
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173 | gotdata_fn_t gotdata, err_fn_t err, void *gotdata_ctx, |
174 | int toplevel) |
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175 | { |
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176 | const char *name; |
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177 | dirhandle d; |
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178 | STRUCT_STAT st; |
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179 | char **names; |
180 | size_t i, nnames, namesize; |
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181 | int statret; |
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182 | |
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183 | /* |
184 | * Special case: at the very top of the scan, we follow a |
185 | * symlink. |
186 | */ |
187 | if (toplevel) |
188 | statret = STAT(*path, &st); |
189 | else |
190 | statret = LSTAT(*path, &st); |
191 | if (statret < 0) { |
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192 | err(gotdata_ctx, "%s: lstat: %s\n", *path, strerror(errno)); |
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193 | return; |
194 | } |
195 | |
196 | if (!gotdata(gotdata_ctx, *path, &st)) |
197 | return; |
198 | |
199 | if (!S_ISDIR(st.st_mode)) |
200 | return; |
201 | |
202 | names = NULL; |
203 | nnames = namesize = 0; |
204 | |
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205 | if (open_dir(*path, &d) < 0) { |
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206 | err(gotdata_ctx, "%s: opendir: %s\n", *path, strerror(errno)); |
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207 | return; |
208 | } |
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209 | while ((name = read_dir(&d)) != NULL) { |
210 | if (name[0] == '.' && (!name[1] || (name[1] == '.' && !name[2]))) { |
211 | /* do nothing - we skip "." and ".." */ |
212 | } else { |
213 | if (nnames >= namesize) { |
214 | namesize = nnames * 3 / 2 + 64; |
215 | names = sresize(names, namesize, char *); |
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216 | } |
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217 | names[nnames++] = dupstr(name); |
218 | } |
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219 | } |
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220 | close_dir(&d); |
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221 | |
222 | if (nnames == 0) |
223 | return; |
224 | |
225 | qsort(names, nnames, sizeof(*names), str_cmp); |
226 | |
227 | for (i = 0; i < nnames; i++) { |
228 | size_t newpathlen = pathlen + 1 + strlen(names[i]); |
229 | if (*pathsize <= newpathlen) { |
230 | *pathsize = newpathlen * 3 / 2 + 256; |
231 | *path = sresize(*path, *pathsize, char); |
232 | } |
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233 | /* |
234 | * Avoid duplicating a slash if we got a trailing one to |
235 | * begin with (i.e. if we're starting the scan in '/' itself). |
236 | */ |
237 | if (pathlen > 0 && (*path)[pathlen-1] == '/') { |
238 | strcpy(*path + pathlen, names[i]); |
239 | newpathlen--; |
240 | } else { |
241 | sprintf(*path + pathlen, "/%s", names[i]); |
242 | } |
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243 | |
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244 | du_recurse(path, newpathlen, pathsize, gotdata, err, gotdata_ctx, 0); |
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245 | |
246 | sfree(names[i]); |
247 | } |
248 | sfree(names); |
249 | } |
250 | |
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251 | void du(const char *inpath, gotdata_fn_t gotdata, err_fn_t err, |
252 | void *gotdata_ctx) |
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253 | { |
254 | char *path; |
255 | size_t pathlen, pathsize; |
256 | |
257 | pathlen = strlen(inpath); |
258 | pathsize = pathlen + 256; |
259 | path = snewn(pathsize, char); |
260 | strcpy(path, inpath); |
261 | |
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262 | du_recurse(&path, pathlen, &pathsize, gotdata, err, gotdata_ctx, 1); |
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263 | } |