From mboxrd@z Thu Jan 1 00:00:00 1970 From: kaushal Subject: Re: how to the filename Date: Fri, 15 Apr 2005 10:09:16 +0530 Message-ID: <1113539956.5720.40.camel@localhost.localdomain> References: <1113472539.5952.62.camel@localhost.localdomain> <6a00c8d5050414033770f1ab96@mail.gmail.com> <1113478791.5720.34.camel@localhost.localdomain> <425F1CC7.9020900@hq.ntsp.nec.co.jp> Reply-To: kaushal@rocsys.com Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <425F1CC7.9020900@hq.ntsp.nec.co.jp> Sender: linux-c-programming-owner@vger.kernel.org List-Id: Content-Type: text/plain; charset="us-ascii" To: Ron Michael Khu Cc: linux-c Hi Ron, I manned for the call and is not available in my linux box. May be I can download that.Thanks for the response. regards- kaushal. On Fri, 2005-04-15 at 07:15, Ron Michael Khu wrote: > Hmm.. > Im not familiar with the implementation of lsof... but I do know that > with pstat_getproc-related functions like pstat_getfile2(), > it is possible to retrieve information on all the open files of a > certain process(given it's PID). It is even possible to > retrieve information about how many threads a particular process has > created. > > BTW, the attached source code is from the HP/UX man page for > pstat_getfile2(), I dont know if the pstat functions > of hp/ux is the same or is supported in linux. > > And like Mr. Ozgur(altunyurt@itu.edu.tr), I dont know how to retrieve > the filename given only a filedescriptor... > because with pstat_getfile2() Im passing PID's. > > -Ron > > > ,kaushal wrote: > > >Hi Steve, > > Thanks for the response.But how will lsof work for a particular PID.If > >lsof can print all the files by their names then why can't any c > >program?The idea was to prove that the file /dev/pts/9 or some no. is > >opened by the bash and to it are the stdin,stdout and stderr > >associated.For that ,the fds 0,1,and 2 are supposed to point to the same > >file /dev/pts/9 or say /dev/tty3 .... > >This can be proved using lsof -p .But how to prove > >that from within a c program?This lead to the sol if we can get the > >filename from the file descriptor and print it on the screen. > > > >regards- > >kaushal. > >On Thu, 2005-04-14 at 16:07, Steve Graegert wrote: > > > > > >>On 4/14/05, kaushal wrote: > >> > >> > >>>Hello all, > >>> How can I get the filename/pathname given the open file descriptor?Does > >>>fstat provide this feature internally?Can somebody give the code snippet > >>>for this. > >>> > >>> > >>There is no such thing. It is not possible to obtain a FD's filename > >>reliably. Unless you are absolutely sure that this particular FD > >>points to a file (or directory) and not to a socket, pipe or > >>something similar, you will not be able to use fstat reliably. Which > >>of stat's fields are suggesting to be helpful reagarding to your > >>problem? st_ino? How would you locate a file based on its file ID? > >>This would require scanning the complete file system (and probably > >>more than one). Another problem is, that an FD might be associated > >>with other files at the same time or files can be stored inside a > >>directory that you can't read due to lack of sufficient permissions. > >>What you are looking for is some kind of reverse lookup to unwind the > >>many-to-one relationship of files and inodes. > >> > >>A couple of years ago Floyd Davidson suggested some code that may > >>point you to the right direction (not tested): > >> > >>/* A demo program to locate file names related to an inode number */ > >> > >>#include > >>#include > >>#include > >>#include > >>#include > >>#include > >>#include > >> > >>void scan_list(char *curdir, struct dirent **ptr_nl, int dirs); > >>int file_select(const struct dirent *nl); > >> > >>ino_t inode; > >>char curdir[PATH_MAX] = "."; /* default search directory */ > >> > >>int > >>main(int argc, char **argv) > >>{ > >> struct dirent **namelist; > >> struct stat st; > >> > >> if (argc < 2 || argc > 3) { > >> fprintf(stderr,"usage: %s inode [directory]\n", argv[0]); > >> exit(EXIT_FAILURE); > >> } > >> inode = strtoul(argv[1], NULL, 10); > >> if (!inode) { > >> fprintf(stderr,"Error: invalid inode\n"); > >> exit(EXIT_FAILURE); > >> } > >> if (argc == 3 && !lstat(argv[2], &st) && S_ISDIR(st.st_mode)) { > >> strcpy(curdir, argv[2]); > >> } > >> > >> scan_list(curdir, namelist, > >> scandir(curdir, &namelist, file_select, alphasort)); > >> return EXIT_SUCCESS; > >>} > >> > >>/* > >> * returns 1 for directories, otherwise 0 > >> * and displays any filename which matches inode. > >> */ > >>int > >>file_select(const struct dirent *nl) > >>{ > >> struct stat st; > >> char curfile[PATH_MAX]; > >> > >> sprintf(curfile, "%s/%s", curdir, nl->d_name); > >> if (0 == lstat(curfile, &st)) { > >> /* report a matching inode number */ > >> if (st.st_ino == inode) { > >> printf(" %6lu %-20s \n", (unsigned long) st.st_ino, curfile); > >> } > >> /* skip these directories */ > >> if (!strcmp(nl->d_name, ".") || !strcmp(nl->d_name, "..")) { > >> return 0; > >> } > >> /* otherwise list all directories */ > >> if (S_ISDIR(st.st_mode)) { > >> return 1; > >> } > >> } return 0; > >>} > >> > >>/* descend through all directories */ > >>void > >>scan_list(char *olddir, struct dirent **ptr_nl, int dirs) > >>{ > >> char savedir[PATH_MAX]; > >> int i; > >> struct dirent **namelist; > >> > >> if (dirs > 0) { > >> for (i = 0; i < dirs; ++i) { > >> strcpy(savedir, curdir); > >> sprintf(curdir,"%s/%s", olddir, ptr_nl[i]->d_name); > >> scan_list(curdir, namelist, > >> scandir(curdir, &namelist, file_select, alphasort)); > >> strcpy(curdir, savedir); > >> } > >> } > >>} > >> > >>/* End of demo program */ > >> > >>Kind Regards > >> > >> \Steve > >> > >>-- > >> > >>Steve Graegert > >>Independent Software Consultant {C/C++ && Java && .NET} > >>Mobile: +49 (176) 21 24 88 69 > >>Office: +49 (9131) 71 26 40 9 > >> > >> > > > >- > >To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in > >the body of a message to majordomo@vger.kernel.org > >More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > > > > ______________________________________________________________________ > #include > #include > #include > #include > > int main( int argc, char *argv[] ) > { > #define BURST ((size_t)10) > struct pst_fileinfo2 psf[BURST]; > int i, count; > int idx = 0; /* index within the context */ > > if ( argc != 2 ) > { > printf( "args: \n" ); > exit( 1 ); > } > pid_t target = atoi( argv[1] ); > > (void)printf("Open files for process PID %d\n", target); > > /* loop until all fetched */ > while ((count = pstat_getfile2(psf, sizeof(struct pst_fileinfo2), > BURST, idx, target)) > 0) { > /* process them (max of BURST) at a time */ > for (i = 0; i < count; i++) { > (void)printf("fd #%d\tFSid %x:%x\tfileid %d\n", > psf[i].psf_fd, > psf[i].psf_id.psf_fsid.psfs_id, > psf[i].psf_id.psf_fsid.psfs_type, > psf[i].psf_id.psf_fileid); > } > > /* > * Now go back and do it again, using the > * next index after the current 'burst' > */ > idx = psf[count-1].psf_fd + 1; > } > if (count == -1) > perror("pstat_getfile2()"); > > #undef BURST > } >