From: Ben Pfaff Date: Tue, 26 Oct 2004 06:44:55 +0000 (+0000) Subject: Revise. X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c9316bcb6319d5f6058ade05281a3e278105729a;p=pintos-anon Revise. --- diff --git a/doc/userprog.texi b/doc/userprog.texi index 38810e7..525e8ce 100644 --- a/doc/userprog.texi +++ b/doc/userprog.texi @@ -248,10 +248,11 @@ requirements: @itemize @bullet @item The kernel should print out the program's name and exit status -whenever a process exits, e.g.@: @code{shell: exit(-1)}. The name -printed should be the full name passed to @func{process_execute}, -except that it is acceptable to truncate it to 15 characters to allow -for the limited space in @struct{thread}. +whenever a process terminates, e.g.@: @code{shell: exit(-1)}, whether +termination is due to a call to the @code{exit} system call or for +another reason. The name printed should be the full name passed to +@func{process_execute}, except that it is acceptable to truncate it to +15 characters to allow for the limited space in @struct{thread}. @item Aside from this, the kernel should print out no other messages that @@ -341,10 +342,11 @@ a successful exit. Other values may be used to indicate user-defined conditions (usually errors). @item SYS_exec -@itemx pid_t exec (const char *@var{file}) -Run the executable in @var{file} and return the new process's program -id (pid). If there is an error loading this program, returns pid -1, -which otherwise should not be a valid id number. +@itemx pid_t exec (const char *@var{cmd_line}) +Runs the executable whose name is given in @var{cmd_line}, passing any +given arguments, and returns the new process's program id (pid). If +there is an error loading this program, returns pid -1, which +otherwise should not be a valid id number. @item SYS_join @itemx int join (pid_t @var{pid}) @@ -384,8 +386,9 @@ Returns the size, in bytes, of the file open as @var{fd}. @item SYS_read @itemx int read (int @var{fd}, void *@var{buffer}, unsigned @var{size}) Read @var{size} bytes from the file open as @var{fd} into -@var{buffer}. Returns the number of bytes actually read, or -1 if the -file could not be read. Fd 0 reads from the keyboard using +@var{buffer}. Returns the number of bytes actually read (0 at end of +file), or -1 if the file could not be read (due to a condition other +than end of file). Fd 0 reads from the keyboard using @func{kbd_getc}. @item SYS_write @@ -400,6 +403,14 @@ Changes the next byte to be read or written in open file @var{fd} to @var{position}, expressed in bytes from the beginning of the file. (Thus, a @var{position} of 0 is the file's start.) +A seek past the current end of a file is not an error. A later read +obtains 0 bytes, indicating end of file. A later write extends the +file, filling any unwritten gap with zeros. (However, in Pintos files +have a fixed length until project 4 is complete, so writes past end of +file will return an error.) These semantics are implemented in the +file system and do not require any special effort in system call +implementation. + @item SYS_tell @itemx unsigned tell (int @var{fd}) Returns the position of the next byte to be read or written in open