0b76964ae
Denis Vlasenko
2008-07-24
Subject
ash: explain redirect code a bit
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shell/ash.c+39 -29
| @@ -594,8 +594,8 @@ struct nfile { | |
| struct ndup { | |
| smallint type; | |
| - | union node *next; |
| - | int fd; |
| + | union node *next; /* must match nfile's layout */ |
| + | int fd; /* must match nfile's layout */ |
| int dupfd; | |
| union node *vname; | |
| }; | |
| @@ -1634,12 +1634,6 @@ nextopt(const char *optstring) | |
| * The parsefile structure pointed to by the global variable parsefile | |
| * contains information about the current file being read. | |
| */ | |
| - | struct redirtab { |
| - | struct redirtab *next; |
| - | int renamed[10]; |
| - | int nullredirs; |
| - | }; |
| - | |
| struct shparam { | |
| int nparam; /* # of positional parameters (without $0) */ | |
| #if ENABLE_ASH_GETOPTS | |
| @@ -1765,6 +1759,7 @@ static const struct { | |
| #endif | |
| }; | |
| + | struct redirtab; |
| struct globals_var { | |
| struct shparam shellparam; /* $@ current positional parameters */ | |
| @@ -1777,7 +1772,7 @@ struct globals_var { | |
| extern struct globals_var *const ash_ptr_to_globals_var; | |
| #define G_var (*ash_ptr_to_globals_var) | |
| #define shellparam (G_var.shellparam ) | |
| - | #define redirlist (G_var.redirlist ) |
| + | //#define redirlist (G_var.redirlist ) |
| #define g_nullredirs (G_var.g_nullredirs ) | |
| #define preverrout_fd (G_var.preverrout_fd) | |
| #define vartab (G_var.vartab ) | |
| @@ -4767,6 +4762,7 @@ openhere(union node *redir) | |
| } | |
| } | |
| if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) { | |
| + | /* child */ |
| close(pip[0]); | |
| signal(SIGINT, SIG_IGN); | |
| signal(SIGQUIT, SIG_IGN); | |
| @@ -4777,7 +4773,7 @@ openhere(union node *redir) | |
| signal(SIGPIPE, SIG_DFL); | |
| if (redir->type == NHERE) | |
| full_write(pip[1], redir->nhere.doc->narg.text, len); | |
| - | else |
| + | else /* NXHERE */ |
| expandhere(redir->nhere.doc, pip[1]); | |
| _exit(EXIT_SUCCESS); | |
| } | |
| @@ -4832,10 +4828,10 @@ openredirect(union node *redir) | |
| abort(); | |
| #endif | |
| /* Fall through to eliminate warning. */ | |
| - | case NTOFD: |
| - | case NFROMFD: |
| - | f = -1; |
| - | break; |
| + | // case NTOFD: |
| + | // case NFROMFD: |
| + | // f = -1; |
| + | // break; |
| case NHERE: | |
| case NXHERE: | |
| f = openhere(redir); | |
| @@ -4873,19 +4869,26 @@ dupredirect(union node *redir, int f) | |
| { | |
| int fd = redir->nfile.fd; | |
| - | if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) { |
| + | if (f < 0) { /* redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD */ |
| if (redir->ndup.dupfd >= 0) { /* if not ">&-" */ | |
| copyfd(redir->ndup.dupfd, fd); | |
| } | |
| return; | |
| } | |
| - | |
| if (f != fd) { | |
| copyfd(f, fd); | |
| close(f); | |
| } | |
| } | |
| + | /**/ |
| + | struct redirtab { |
| + | struct redirtab *next; |
| + | int renamed[10]; |
| + | int nullredirs; |
| + | }; |
| + | #define redirlist (G_var.redirlist ) |
| + | |
| /* | |
| * Process a list of redirection commands. If the REDIR_PUSH flag is set, | |
| * old file descriptors are stashed away so that the redirection can be | |
| @@ -4921,36 +4924,43 @@ redirect(union node *redir, int flags) | |
| } | |
| do { | |
| fd = redir->nfile.fd; | |
| - | if ((redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) |
| - | && redir->ndup.dupfd == fd) |
| - | continue; /* redirect from/to same file descriptor */ |
| - | |
| - | newfd = openredirect(redir); |
| - | if (fd == newfd) { |
| - | /* Descriptor wasn't open before redirect. |
| - | * Mark it for close in the future */ |
| - | if (sv && sv->renamed[fd] == EMPTY) |
| - | sv->renamed[fd] = CLOSED; |
| - | continue; |
| + | if (redir->nfile.type == NTOFD || redir->nfile.type == NFROMFD) { |
| + | if (redir->ndup.dupfd == fd) |
| + | continue; /* redirect from/to same file descriptor */ |
| + | newfd = -1; |
| + | } else { |
| + | newfd = openredirect(redir); /* always >= 0 */ |
| + | if (fd == newfd) { |
| + | /* Descriptor wasn't open before redirect. |
| + | * Mark it for close in the future */ |
| + | if (sv && sv->renamed[fd] == EMPTY) |
| + | sv->renamed[fd] = CLOSED; |
| + | continue; |
| + | } |
| } | |
| if (sv && sv->renamed[fd] == EMPTY) { | |
| + | /* Copy old descriptor */ |
| i = fcntl(fd, F_DUPFD, 10); | |
| - | |
| if (i == -1) { | |
| i = errno; | |
| - | if (i != EBADF) { |
| + | if (i != EBADF) { /* strange error */ |
| close(newfd); | |
| errno = i; | |
| ash_msg_and_raise_error("%d: %m", fd); | |
| /* NOTREACHED */ | |
| } | |
| + | /* it is not open - ok */ |
| } else { | |
| + | /* it is open, save its copy */ |
| sv->renamed[fd] = i; | |
| close(fd); | |
| } | |
| } else { | |
| close(fd); | |
| } | |
| + | /* Here fd is closed */ |
| + | /* NTOFD/NFROMFD: copy redir->ndup.dupfd to fd */ |
| + | /* else: move newfd to fd */ |
| dupredirect(redir, newfd); | |
| } while ((redir = redir->nfile.next) != NULL); | |
| INT_ON; | |