+/* prsvunix.c */
+
+/* This file contains the UNIX-specific parts of the "elvprsv" program. */
+
+#if OSK
+#define ELVPRSV
+#include "osk.c"
+#else
+#include <sys/stat.h>
+#include <pwd.h>
+#endif
+#ifndef __STDC__
+/* some older systems don't declare this in pwd.h, I guess. */
+extern struct passwd *getpwuid();
+#endif
+
+#if ANY_UNIX /* { */
+/* Since elvprsv runs as SUID-root, we need a *secure* version of popen() */
+#define popen safe_popen
+#define pclose safe_pclose
+
+/* This function is similar to the standard popen() function, except for...
+ * 1) It doesn't use the shell, for security reasons.
+ * 2) Shell services are not supported, including quoting.
+ * 3) The mode can only be "w". "r" is not supported.
+ * 4) No more than 9 arguments can be given, including the command.
+ */
+/*ARGSUSED*/
+static FILE *safe_popen(cmd, mode)
+ char *cmd; /* the filename of the program to be run */
+ char *mode; /* "w", ignored */
+{
+ char path[100];/* full pathname of argv[0] */
+ char *argv[10];/* the arguments */
+ int r0w1[2];/* the pipe fd's */
+ int i;
+ FILE *fp;
+
+ /* parse the arguments */
+ for (i = 0; i < 9 && *cmd; i++)
+ {
+ /* remember where this arg starts */
+ argv[i] = cmd;
+
+ /* move to the end of the argument */
+ do
+ {
+ cmd++;
+ } while (*cmd && *cmd != ' ');
+
+ /* then mark end of arg & skip to next */
+ while (*cmd && *cmd == ' ')
+ {
+ *cmd++ = '\0';
+ }
+printf("argv[%d]=\"%s\"\n", i, argv[i]);
+ }
+ argv[i] = (char *)0;
+
+ /* make the pipe */
+ if (pipe(r0w1) < 0)
+ {
+perror("pipe()");
+ return (FILE *)0; /* pipe failed */
+ }
+
+ switch (fork())
+ {
+ case -1: /* error */
+perror("fork()");
+ return (FILE *)0;
+
+ case 0: /* child */
+ /* close the "write" end of the pipe */
+ close(r0w1[1]);
+
+ /* redirect stdin to come from the "read" end of the pipe */
+ close(0);
+ dup(r0w1[0]);
+ close(r0w1[0]);
+
+ /* exec the shell to run the command */
+ if (*argv[0] != '/')
+ {
+ /* no path, try "/bin/argv[0]" */
+ strcpy(path, "/bin/");
+ strcat(path, argv[0]);
+ execv(path, argv);
+perror(path);
+
+ /* if that failed, then try "/usr/bin/argv[0]" */
+ strcpy(path, "/usr/bin/");
+ strcat(path, argv[0]);
+ execv(path, argv);
+perror(path);
+ }
+ else
+ {
+ /* full pathname given, so use it */
+ execv(argv[0], argv);
+perror(argv[0]);
+ }
+
+ /* if we get here, exec failed */
+ exit(1);
+
+ default: /* parent */
+ /* close the "read" end of the pipe */
+ close(r0w1[0]);
+
+ /* convert the "write" fd into a (FILE *) */
+ fp = fdopen(r0w1[1], "w");
+ return fp;
+ }
+ /*NOTREACHED*/
+}
+
+
+/* This function closes the pipe opened by popen(), and returns 0 for success */
+static int safe_pclose(fp)
+ FILE *fp; /* value returned by popen() */
+{
+ int status;
+
+ /* close the file, and return the defunct child's exit status */
+ fclose(fp);
+ wait(&status);
+ return status;
+}
+#endif /* } ANY UNIX */
+
+
+/* This variable is used to add extra error messages for mail sent to root */
+char *ps;
+
+/* This function returns the login name of the owner of a file */
+char *ownername(filename)
+ char *filename; /* name of a file */
+{
+ struct stat st;
+ struct passwd *pw;
+
+ /* stat the file, to get its uid */
+ if (stat(filename, &st) < 0)
+ {
+ ps = "stat() failed";
+ return "root";
+ }
+
+ /* get the /etc/passwd entry for that user */
+ pw = getpwuid(st.st_uid);
+ if (!pw)
+ {
+ ps = "uid not found in password file";
+ return "root";
+ }
+
+ /* return the user's name */
+ return pw->pw_name;
+}
+
+
+/* This function sends a mail message to a given user, saying that a file
+ * has been preserved.
+ */
+void mail(user, file, when)
+ char *user; /* name of user who should receive the mail */
+ char *file; /* name of original text file that was preserved */
+ char *when; /* description of why the file was preserved */
+{
+ char cmd[80];/* buffer used for constructing a "mail" command */
+ FILE *m; /* stream used for giving text to the "mail" program */
+ char *base; /* basename of the file */
+
+ /* separate the directory name from the basename. */
+ for (base = file + strlen(file); --base > file && *base != SLASH; )
+ {
+ }
+ if (*base == SLASH)
+ {
+ *base++ = '\0';
+ }
+
+ /* for anonymous buffers, pretend the name was "foo" */
+ if (!strcmp(base, "*"))
+ {
+ base = "foo";
+ }
+
+ /* open a pipe to the "mail" program */
+#if OSK
+ sprintf(cmd, "mail \"-s=%s preserved!\" %s", base, user);
+#else /* ANY_UNIX */
+ sprintf(cmd, "mail -s Graceland %s", user);
+#endif
+ m = popen(cmd, "w");
+ if (!m)
+ {
+ perror(cmd);
+ /* Can't send mail! Hope the user figures it out. */
+ return;
+ }
+
+ /* Tell the user that the file was preserved */
+ fprintf(m, "A version of your file \"%s%c%s\"\n", file, SLASH, base);
+ fprintf(m, "was preserved when %s.\n", when);
+ fprintf(m, "To recover this file, do the following:\n");
+ fprintf(m, "\n");
+#if OSK
+ fprintf(m, " chd %s\n", file);
+#else /* ANY_UNIX */
+ fprintf(m, " cd %s\n", file);
+#endif
+ fprintf(m, " elvisrecover %s\n", base);
+ fprintf(m, "\n");
+ fprintf(m, "With fond wishes for a speedy recovery,\n");
+ fprintf(m, " Elvis\n");
+ if (ps)
+ {
+ fprintf(m, "\nP.S. %s\n", ps);
+ ps = (char *)0;
+ }
+
+ /* close the stream */
+ pclose(m);
+}
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