src/runtime/wrap.c

   1 /*
   2  * wrappers around low-level operations to provide a simpler interface
   3  * to the operations that Lisp needs
   4  *
   5  * The functions in this file are typically called directly from Lisp.
   6  * Thus, when their signature changes, they don't need updates in a .h
   7  * file somewhere, but they do need updates in the Lisp code. FIXME:
   8  * It would be nice to enforce this at compile time. It mighn't even
   9  * be all that hard: make the cross-compiler versions of DEFINE-ALIEN-FOO
  10  * macros accumulate strings in a list which then gets written out at
  11  * the end of sbcl2.h at the end of cross-compilation, then rerun
  12  * 'make' in src/runtime/ using the new sbcl2.h as sbcl.h (and make
  13  * sure that all the files in src/runtime/ include sbcl.h). */
  14
  15 /*
  16  * This software is part of the SBCL system. See the README file for
  17  * more information.
  18  *
  19  * This software is derived from the CMU CL system, which was
  20  * written at Carnegie Mellon University and released into the
  21  * public domain. The software is in the public domain and is
  22  * provided with absolutely no warranty. See the COPYING and CREDITS
  23  * files for more information.
  24  */
  25
  26 #include <sys/types.h>
  27 #include <dirent.h>
  28 #include <sys/stat.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32 #include <pwd.h>
  33 #include <stdio.h>
  34
  35 #include "sbcl.h"
  36 #include "runtime.h"
  37 #include "util.h"
  38
  39 /* Although it might seem as though this should be in some standard
  40    Unix header, according to Perry E. Metzger, in a message on
  41    sbcl-devel dated 2004-03-29, this is the POSIXly-correct way of
  42    using environ: by an explicit declaration.  -- CSR, 2004-03-30 */
  43 extern char **environ;
  44 \f
  45 /*
  46  * stuff needed by CL:DIRECTORY and other Lisp directory operations
  47  */
  48
  49 /* Unix directory operations think of "." and ".." as filenames, but
  50  * Lisp directory operations do not. */
  51 int
  52 is_lispy_filename(const char *filename)
  53 {
  54     return strcmp(filename, ".") && strcmp(filename, "..");
  55 }
  56
  57 /* Return a zero-terminated array of strings holding the Lispy filenames
  58  * (i.e. excluding the Unix magic "." and "..") in the named directory. */
  59 char**
  60 alloc_directory_lispy_filenames(const char *directory_name)
  61 {
  62     DIR *dir_ptr = opendir(directory_name);
  63     char **result = 0;
  64
  65     if (dir_ptr) { /* if opendir success */
  66
  67         struct voidacc va;
  68
  69         if (0 == voidacc_ctor(&va)) { /* if voidacc_ctor success */
  70             struct dirent *dirent_ptr;
  71
  72             while ( (dirent_ptr = readdir(dir_ptr)) ) { /* until end of data */
  73                 char* original_name = dirent_ptr->d_name;
  74                 if (is_lispy_filename(original_name)) {
  75                     /* strdup(3) is in Linux and *BSD. If you port
  76                      * somewhere else that doesn't have it, it's easy
  77                      * to reimplement. */
  78                     char* dup_name = strdup(original_name);
  79                     if (!dup_name) { /* if strdup failure */
  80                         goto dtors;
  81                     }
  82                     if (voidacc_acc(&va, dup_name)) { /* if acc failure */
  83                         goto dtors;
  84                     }
  85                 }
  86             }
  87             result = (char**)voidacc_give_away_result(&va);
  88         }
  89
  90     dtors:
  91         voidacc_dtor(&va);
  92         /* ignoring closedir(3) return code, since what could we do?
  93          *
  94          * "Never ask questions you don't want to know the answer to."
  95          * -- William Irving Zumwalt (Rich Cook, _The Wizardry Quested_) */
  96         closedir(dir_ptr);
  97     }
  98
  99     return result;
 100 }
 101
 102 /* Free a result returned by alloc_directory_lispy_filenames(). */
 103 void
 104 free_directory_lispy_filenames(char** directory_lispy_filenames)
 105 {
 106     char** p;
 107
 108     /* Free the strings. */
 109     for (p = directory_lispy_filenames; *p; ++p) {
 110         free(*p);
 111     }
 112
 113     /* Free the table of strings. */
 114     free(directory_lispy_filenames);
 115 }
 116 \f
 117 /*
 118  * readlink(2) stuff
 119  */
 120
 121 /* a wrapped version of readlink(2):
 122  *   -- If path isn't a symlink, or is a broken symlink, return 0.
 123  *   -- If path is a symlink, return a newly allocated string holding
 124  *      the thing it's linked to. */
 125 char *
 126 wrapped_readlink(char *path)
 127 {
 128     int bufsiz = strlen(path) + 16;
 129     while (1) {
 130         char *result = malloc(bufsiz);
 131         int n_read = readlink(path, result, bufsiz);
 132         if (n_read < 0) {
 133             free(result);
 134             return 0;
 135         } else if (n_read < bufsiz) {
 136             result[n_read] = 0;
 137             return result;
 138         } else {
 139             free(result);
 140             bufsiz *= 2;
 141         }
 142     }
 143 }
 144 \f
 145 /*
 146  * stat(2) stuff
 147  */
 148
 149 /* As of 0.6.12, the FFI can't handle 64-bit values. For now, we use
 150  * these munged-to-32-bits values for might-be-64-bit slots of
 151  * stat_wrapper as a workaround, so that at least we can still work
 152  * when values are small.
 153  *
 154  * FIXME: But of course we should fix the FFI so that we can use the
 155  * actual 64-bit values instead.  In fact, we probably have by now
 156  * (2003-10-03) on all working platforms except MIPS and HPPA; if some
 157  * motivated spark would simply fix those, this hack could go away.
 158  * -- CSR, 2003-10-03 */
 159 typedef u32 ffi_dev_t; /* since Linux dev_t can be 64 bits */
 160 typedef u32 ffi_off_t; /* since OpenBSD 2.8 st_size is 64 bits */
 161
 162 /* a representation of stat(2) results which doesn't depend on CPU or OS */
 163 struct stat_wrapper {
 164     /* KLUDGE: The verbose wrapped_st_ prefixes are to protect us from
 165      * the C preprocessor as wielded by the fiends of OpenBSD, who do
 166      * things like
 167      *    #define st_atime        st_atimespec.tv_sec
 168      * I remember when I was young and innocent, I read about how the
 169      * C preprocessor isn't to be used to globally munge random
 170      * lowercase symbols like this, because things like this could
 171      * happen, and I nodded sagely. But now I know better.:-| This is
 172      * another entry for Dan Barlow's ongoing episodic rant about C
 173      * header files, I guess.. -- WHN 2001-05-10 */
 174     ffi_dev_t     wrapped_st_dev;         /* device */
 175     ino_t         wrapped_st_ino;         /* inode */
 176     mode_t        wrapped_st_mode;        /* protection */
 177     nlink_t       wrapped_st_nlink;       /* number of hard links */
 178     uid_t         wrapped_st_uid;         /* user ID of owner */
 179     gid_t         wrapped_st_gid;         /* group ID of owner */
 180     ffi_dev_t     wrapped_st_rdev;        /* device type (if inode device) */
 181     ffi_off_t     wrapped_st_size;        /* total size, in bytes */
 182     unsigned long wrapped_st_blksize;     /* blocksize for filesystem I/O */
 183     unsigned long wrapped_st_blocks;      /* number of blocks allocated */
 184     time_t        wrapped_st_atime;       /* time_t of last access */
 185     time_t        wrapped_st_mtime;       /* time_t of last modification */
 186     time_t        wrapped_st_ctime;       /* time_t of last change */
 187 };
 188
 189 static void
 190 copy_to_stat_wrapper(struct stat_wrapper *to, struct stat *from)
 191 {
 192 #define FROB(stem) to->wrapped_st_##stem = from->st_##stem
 193     FROB(dev);
 194     FROB(ino);
 195     FROB(mode);
 196     FROB(nlink);
 197     FROB(uid);
 198     FROB(gid);
 199     FROB(rdev);
 200     FROB(size);
 201     FROB(blksize);
 202     FROB(blocks);
 203     FROB(atime);
 204     FROB(mtime);
 205     FROB(ctime);
 206 #undef FROB
 207 }
 208
 209 int
 210 stat_wrapper(const char *file_name, struct stat_wrapper *buf)
 211 {
 212     struct stat real_buf;
 213     int ret;
 214     if ((ret = stat(file_name,&real_buf)) >= 0)
 215         copy_to_stat_wrapper(buf, &real_buf);
 216     return ret;
 217 }
 218
 219 int
 220 lstat_wrapper(const char *file_name, struct stat_wrapper *buf)
 221 {
 222     struct stat real_buf;
 223     int ret;
 224     if ((ret = lstat(file_name,&real_buf)) >= 0)
 225         copy_to_stat_wrapper(buf, &real_buf);
 226     return ret;
 227 }
 228
 229 int
 230 fstat_wrapper(int filedes, struct stat_wrapper *buf)
 231 {
 232     struct stat real_buf;
 233     int ret;
 234     if ((ret = fstat(filedes,&real_buf)) >= 0)
 235         copy_to_stat_wrapper(buf, &real_buf);
 236     return ret;
 237 }
 238 \f
 239 /*
 240  * getpwuid() stuff
 241  */
 242
 243 /* Return a newly-allocated string holding the username for "uid", or
 244  * NULL if there's no such user.
 245  *
 246  * KLUDGE: We also return NULL if malloc() runs out of memory
 247  * (returning strdup() result) since it's not clear how to handle that
 248  * error better. -- WHN 2001-12-28 */
 249 char *
 250 uid_username(int uid)
 251 {
 252     struct passwd *p = getpwuid(uid);
 253     if (p) {
 254         /* The object *p is a static struct which'll be overwritten by
 255          * the next call to getpwuid(), so it'd be unsafe to return
 256          * p->pw_name without copying. */
 257         return strdup(p->pw_name);
 258     } else {
 259         return 0;
 260     }
 261 }
 262
 263 char *
 264 uid_homedir(uid_t uid)
 265 {
 266     struct passwd *p = getpwuid(uid);
 267     if(p) {
 268         /* Let's be careful about this, shall we? */
 269         size_t len = strlen(p->pw_dir);
 270         if (p->pw_dir[len-1] == '/') {
 271             return strdup(p->pw_dir);
 272         } else {
 273             char *result = malloc(len + 2);
 274             if (result) {
 275                 int nchars = sprintf(result,"%s/",p->pw_dir);
 276                 if (nchars == len + 1) {
 277                     return result;
 278                 } else {
 279                     return 0;
 280                 }
 281             } else {
 282                 return 0;
 283             }
 284         }
 285     } else {
 286         return 0;
 287     }
 288 }
 289 \f
 290 /*
 291  * functions to get miscellaneous C-level variables
 292  *
 293  * (Doing this by calling functions lets us borrow the smarts of the C
 294  * linker, so that things don't blow up when libc versions and thus
 295  * variable locations change between compile time and run time.)
 296  */
 297
 298 char **
 299 wrapped_environ()
 300 {
 301     return environ;
 302 }