diff options
Diffstat (limited to 'libbb/xfuncs.c')
| -rw-r--r-- | libbb/xfuncs.c | 109 |
1 files changed, 76 insertions, 33 deletions
diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c index a926beb83..cfb1c29ac 100644 --- a/libbb/xfuncs.c +++ b/libbb/xfuncs.c @@ -11,8 +11,13 @@ #include "busybox.h" +/* All the functions starting with "x" call bb_error_msg_and_die() if they + * fail, so callers never need to check for errors. If it returned, it + * succeeded. */ + #ifndef DMALLOC #ifdef L_xmalloc +// Die if we can't allocate size bytes of memory. void *xmalloc(size_t size) { void *ptr = malloc(size); @@ -23,6 +28,9 @@ void *xmalloc(size_t size) #endif #ifdef L_xrealloc +// Die if we can't resize previously allocated memory. (This returns a pointer +// to the new memory, which may or may not be the same as the old memory. +// It'll copy the contents to a new chunk and free the old one if necessary.) void *xrealloc(void *ptr, size_t size) { ptr = realloc(ptr, size); @@ -33,6 +41,7 @@ void *xrealloc(void *ptr, size_t size) #endif #ifdef L_xzalloc +// Die if we can't allocate and zero size bytes of memory. void *xzalloc(size_t size) { void *ptr = xmalloc(size); @@ -44,7 +53,8 @@ void *xzalloc(size_t size) #endif /* DMALLOC */ #ifdef L_xstrdup -char * xstrdup (const char *s) +// Die if we can't copy a string to freshly allocated memory. +char * xstrdup(const char *s) { char *t; @@ -61,7 +71,9 @@ char * xstrdup (const char *s) #endif #ifdef L_xstrndup -char * xstrndup (const char *s, int n) +// Die if we can't allocate n+1 bytes (space for the null terminator) and copy +// the (possibly truncated to length n) string into it. +char * xstrndup(const char *s, int n) { char *t; @@ -75,6 +87,8 @@ char * xstrndup (const char *s, int n) #endif #ifdef L_xfopen +// Die if we can't open a file and return a FILE * to it. +// Notice we haven't got xfread(), This is for use with fscanf() and friends. FILE *xfopen(const char *path, const char *mode) { FILE *fp; @@ -85,13 +99,18 @@ FILE *xfopen(const char *path, const char *mode) #endif #ifdef L_xopen +// Die if we can't open an existing file and return an fd. int xopen(const char *pathname, int flags) { + if (ENABLE_DEBUG && (flags && O_CREAT)) + bb_error_msg_and_die("xopen() with O_CREAT\n"); + return xopen3(pathname, flags, 0777); } #endif #ifdef L_xopen3 +// Die if we can't open a new file and return an fd. int xopen3(const char *pathname, int flags, int mode) { int ret; @@ -105,9 +124,7 @@ int xopen3(const char *pathname, int flags, int mode) #endif #ifdef L_xread - // Die with an error message if we can't read the entire buffer. - void xread(int fd, void *buf, size_t count) { while (count) { @@ -122,9 +139,7 @@ void xread(int fd, void *buf, size_t count) #endif #ifdef L_xwrite - // Die with an error message if we can't write the entire buffer. - void xwrite(int fd, void *buf, size_t count) { while (count) { @@ -139,9 +154,7 @@ void xwrite(int fd, void *buf, size_t count) #endif #ifdef L_xlseek - -// Die if we can't lseek to the right spot. - +// Die with an error message if we can't lseek to the right spot. void xlseek(int fd, off_t offset, int whence) { if (offset != lseek(fd, offset, whence)) bb_error_msg_and_die("lseek"); @@ -149,6 +162,7 @@ void xlseek(int fd, off_t offset, int whence) #endif #ifdef L_xread_char +// Die with an error message if we can't read one character. unsigned char xread_char(int fd) { char tmp; @@ -160,6 +174,7 @@ unsigned char xread_char(int fd) #endif #ifdef L_xferror +// Die with supplied error message if this FILE * has ferror set. void xferror(FILE *fp, const char *fn) { if (ferror(fp)) { @@ -169,6 +184,7 @@ void xferror(FILE *fp, const char *fn) #endif #ifdef L_xferror_stdout +// Die with an error message if stdout has ferror set. void xferror_stdout(void) { xferror(stdout, bb_msg_standard_output); @@ -176,6 +192,7 @@ void xferror_stdout(void) #endif #ifdef L_xfflush_stdout +// Die with an error message if we have trouble flushing stdout. void xfflush_stdout(void) { if (fflush(stdout)) { @@ -185,7 +202,8 @@ void xfflush_stdout(void) #endif #ifdef L_spawn -// This does a fork/exec in one call, using vfork(). +// This does a fork/exec in one call, using vfork(). Return PID of new child, +// -1 for failure. Runs argv[0], searching path if that has no / in it. pid_t spawn(char **argv) { static int failed; @@ -211,6 +229,7 @@ pid_t spawn(char **argv) #endif #ifdef L_xspawn +// Die with an error message if we can't spawn a child process. pid_t xspawn(char **argv) { pid_t pid = spawn(argv); @@ -220,6 +239,7 @@ pid_t xspawn(char **argv) #endif #ifdef L_wait4 +// Wait for the specified child PID to exit, returning child's error return. int wait4pid(int pid) { int status; @@ -232,11 +252,9 @@ int wait4pid(int pid) #endif #ifdef L_itoa -// Largest 32 bit integer is -2 billion plus null terminator. -// Int should always be 32 bits on a Unix-oid system, see -// http://www.unix.org/whitepapers/64bit.html -static char local_buf[12]; - +// Convert unsigned integer to ascii, writing into supplied buffer. A +// truncated result is always null terminated (unless buflen is 0), and +// contains the first few digits of the result ala strncpy. void utoa_to_buf(unsigned n, char *buf, unsigned buflen) { int i, out = 0; @@ -254,15 +272,7 @@ void utoa_to_buf(unsigned n, char *buf, unsigned buflen) } } -// Note: uses static buffer, calling it twice in a row will overwrite. - -char *utoa(unsigned n) -{ - utoa_to_buf(n, local_buf, sizeof(local_buf)); - - return local_buf; -} - +// Convert signed integer to ascii, like utoa_to_buf() void itoa_to_buf(int n, char *buf, unsigned buflen) { if (buflen && n<0) { @@ -273,8 +283,24 @@ void itoa_to_buf(int n, char *buf, unsigned buflen) utoa_to_buf((unsigned)n, buf, buflen); } -// Note: uses static buffer, calling it twice in a row will overwrite. +// The following two functions use a static buffer, so calling either one a +// second time will overwrite previous results. +// +// The largest 32 bit integer is -2 billion plus null terminator, or 12 bytes. +// Int should always be 32 bits on any remotely Unix-like system, see +// http://www.unix.org/whitepapers/64bit.html for the reasons why. +static char local_buf[12]; + +// Convert unsigned integer to ascii using a static buffer (returned). +char *utoa(unsigned n) +{ + utoa_to_buf(n, local_buf, sizeof(local_buf)); + + return local_buf; +} + +// Convert signed integer to ascii using a static buffer (returned). char *itoa(int n) { itoa_to_buf(n, local_buf, sizeof(local_buf)); @@ -284,11 +310,15 @@ char *itoa(int n) #endif #ifdef L_setuid +// Die with an error message if we can't set gid. (Because resource limits may +// limit this user to a given number of processes, and if that fills up the +// setgid() will fail and we'll _still_be_root_, which is bad.) void xsetgid(gid_t gid) { if (setgid(gid)) bb_error_msg_and_die("setgid"); } +// Die with an error message if we cant' set uid. (See xsetgid() for why.) void xsetuid(uid_t uid) { if (setuid(uid)) bb_error_msg_and_die("setuid"); @@ -296,6 +326,7 @@ void xsetuid(uid_t uid) #endif #ifdef L_fdlength +// Return how long the file at fd is, if there's any way to determine it. off_t fdlength(int fd) { off_t bottom = 0, top = 0, pos; @@ -305,7 +336,8 @@ off_t fdlength(int fd) if (ioctl(fd, BLKGETSIZE, &size) >= 0) return size*512; - // If not, do a binary search for the last location we can read. + // If not, do a binary search for the last location we can read. (Some + // block devices don't do BLKGETSIZE right.) do { char temp; @@ -334,6 +366,8 @@ off_t fdlength(int fd) #endif #ifdef L_xasprintf +// Die with an error message if we can't malloc() enough space and do an +// sprintf() into that space. char *xasprintf(const char *format, ...) { va_list p; @@ -362,6 +396,8 @@ char *xasprintf(const char *format, ...) #endif #ifdef L_xprint_and_close_file +// Die with an error message if we can't copy an entire FILE * to stdout, then +// close that file. void xprint_and_close_file(FILE *file) { // copyfd outputs error messages for us. @@ -372,6 +408,7 @@ void xprint_and_close_file(FILE *file) #endif #ifdef L_xchdir +// Die if we can't chdir to a new path. void xchdir(const char *path) { if (chdir(path)) @@ -380,6 +417,7 @@ void xchdir(const char *path) #endif #ifdef L_warn_opendir +// Print a warning message if opendir() fails, but don't die. DIR *warn_opendir(const char *path) { DIR *dp; @@ -393,6 +431,7 @@ DIR *warn_opendir(const char *path) #endif #ifdef L_xopendir +// Die with an error message if opendir() fails. DIR *xopendir(const char *path) { DIR *dp; @@ -405,6 +444,7 @@ DIR *xopendir(const char *path) #ifdef L_xdaemon #ifndef BB_NOMMU +// Die with an error message if we can't daemonize. void xdaemon(int nochdir, int noclose) { if (daemon(nochdir, noclose)) bb_perror_msg_and_die("daemon"); @@ -412,14 +452,8 @@ void xdaemon(int nochdir, int noclose) #endif #endif -#ifdef L_xbind -void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen) -{ - if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind"); -} -#endif - #ifdef L_xsocket +// Die with an error message if we can't open a new socket. int xsocket(int domain, int type, int protocol) { int r = socket(domain, type, protocol); @@ -430,7 +464,16 @@ int xsocket(int domain, int type, int protocol) } #endif +#ifdef L_xbind +// Die with an error message if we can't bind a socket to an address. +void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen) +{ + if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind"); +} +#endif + #ifdef L_xlisten +// Die with an error message if we can't listen for connections on a socket. void xlisten(int s, int backlog) { if (listen(s, backlog)) bb_perror_msg_and_die("listen"); |