Re: [Libmtp-discuss] udev and libmtp: detect a new mtp device based on its USB interface descriptor

[<la...@no...>]

/**
*This program is used to check whether a device is mtp device, it use the infomation exported to sysfs to do this check
*argument:the device path under sysfs for this device
*return:0 means it is a mtp-device, otherwise, return 1;
*usage:mtp_probe devicepath pattern
*'devicepath' is the path for the device under sysfs, 'pattern' is the pattern used to match against
*for eg,mtp_probe /sys/devices/pci0000:00/0000:00:1d.7/usb1/1-8 mtp
*/

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include <string.h>

#define PATH_LENGTH 256

#define LINE_LENGTH 1024
#define ENABLE_LOG

#ifdef ENABLE_LOG
void printlog (const char *format, ...)
{
        FILE *fp;
        fp = fopen("/tmp/probe.txt","a");
        if(NULL != fp)
        {
                va_list args;

                va_start (args, format);
                
                vfprintf(fp,format,args);
                fprintf(fp,"\n");
                fflush(fp);
                fclose(fp);
                va_end (args);
        }
}

#else
void printlog (const char *format, ...)
{
}
#endif


/**
This function check the interface directory for the interface of a device under sysfs,
to see if this device is a mtp device. The check is based on following criteria:
1. has string descriptor with the file name 'interface';
2. the string descriptor contains the specified pattern, indicated by argument 'pattern'

return 1 if above criteria meets, thus it is a mtp device, otherwise, return 0.
*/
int check_interface_subdir(const char* dirname, const char* pattern)
{
	const char str_descriptor[] = "interface"; //the filename under sysfs for interface string descriptor
	DIR *dir = NULL;
	struct dirent *entry = NULL;
	char filename[PATH_LENGTH];
	struct stat filestat;
	
	char *buf = NULL; //buf is used to hold the whole contents of the file 'interface'
	char *temp = NULL; //used to hold the content read each time by 'fgets'
	FILE *fp = NULL;
	int ret = 0;//return value

	dir = opendir(dirname);
	if (!dir) {
		printlog("fail to open interface dir:%s\n",dirname);
		return 0;	
	}

	while ((entry = readdir(dir)) != NULL) {
		if ((strcmp(entry->d_name,str_descriptor)) != 0) {
			continue;
		}


		printlog("find interface file\n");
		snprintf(filename,sizeof(filename),"%s/%s",dirname,entry->d_name);
		printlog("interface filename:%s\n",filename);
		
		if ((stat(filename,&filestat)) == 0) {
			int filesize = filestat.st_size;
			printlog("filesize:%d\n",filesize);
			if (filesize > 0) {
				fp = fopen(filename,"r");
				if (!fp) {
					printlog("fail to open file to read\n");
					break;
				}

				buf = (char *)malloc(filesize+1);	
				if (!buf) {
					printlog("fail to alloc memory to read file\n");
					fclose(fp);
					break;					
				}
				memset(buf,0,filesize+1);

				temp = (char *)malloc(LINE_LENGTH);
				if (!temp) {
					printlog("fail to alloc memory for temp\n");
					free(buf);
					fclose(fp);
					break;					
				}
				memset(temp,0,LINE_LENGTH);

				
				while((fgets(temp,LINE_LENGTH,fp)) != NULL) {
					strncat(buf,temp,strlen(temp));
					
				}
				printlog("read out the whole contents:%sstrlen:%d\n",buf,strlen(buf));
				if((strcasestr(buf,pattern)) != NULL) {
					printlog("find the pattern\n");
					ret = 1;					
				} else {
					printlog("not find the pattern\n");
				}
				fclose(fp);
				free(buf);
				free(temp);
							
			} //end of if (size > 0)
			
		} else {
			printlog("fail to get stat of file:\n");
		} //end of if ((stat(filename,&filestat)) == 0)
		
		break;
					
	} //end of while ((entry = readdir(dir)) != NULL)

	closedir(dir);
	return ret;
}

int main(int argc, char** argv)
{
	DIR	*dir = NULL;
	struct dirent *entry = NULL;
	int found = 0;

	if (argc < 3) {
		printlog("Usage:check-mtp-device devicepath pattern\n");
		exit(1);	
	}
	
	printlog("the device path:%s, pattern:%s \n",argv[1],argv[2]);
	dir = opendir(argv[1]);
	if (!dir) {
		printlog("fail to open the dir for device,exit\n");
		return 1;	
	}

	while ((entry = readdir(dir)) != NULL) {
		//Skip directory which begins with '.'
		if (entry->d_type == DT_DIR && entry->d_name[0] != '.') {
			char interfacedir[PATH_LENGTH];
			
			//TODO check if the name of directory be consistent with the pattern of interface directory
			//usb sysfs naming scheme for an interface is like "hubno-portno:configno.interface",eg,"1-8:1.0"
			//currently, just check whether it contains the character ':'
			if((strchr(entry->d_name,':')) == NULL) {
				printlog("skip the dir entry:%s\n",entry->d_name);
				continue;			
			}

			snprintf(interfacedir,	sizeof(interfacedir),"%s/%s",argv[1],entry->d_name);
			printlog("interfacedir to check:%s\n",interfacedir);		
			found = check_interface_subdir(interfacedir,argv[2]);
			if (found) {
				printlog("find the mtp interface\n");
				break;			
			} else {
				continue;			
			}

		} else {
			printlog("skip the entry:%s\n",entry->d_name);
			continue;		
		}
	} //end of while ((entry = readdir(dir)) != NULL)

	closedir(dir);

	if (found) {
		printlog("found mtp device\n");
		return 0;	
	} else {
		printlog("not found mtp device \n");
		return 1;
	}
			
}