0.libusb的介紹：

1.環境：vmware下Ubuntu12.04

3.解壓原始碼tar xjvf libusb-1.0.9.tar.bz2 按照INSTALL檔案給出的提示進行安裝：主要分為./configure ->make -> make install

4.安裝過程如下：

configure略去......（記得./configure命令時可能沒反應，後查明是沒有執行權，可以使用 sudo chmod +x ***來增加執行權，整個過程中使用sudo來進行）

/* make的動作主要是編譯libusb的原始碼 */

[[email protected] libusb-1.0.9]# make

make  all-recursive
make[1]: Entering directory `/share/libusb-1.0.9'
Making all in libusb
make[2]: Entering directory `/share/libusb-1.0.9/libusb'
  CC     libusb_1_0_la-core.lo
  CC     libusb_1_0_la-descriptor.lo
  CC     libusb_1_0_la-io.lo
  CC     libusb_1_0_la-sync.lo
  CC     libusb_1_0_la-linux_usbfs.lo
  CC     libusb_1_0_la-threads_posix.lo
  CCLD   libusb-1.0.la
make[2]: Leaving directory `/share/libusb-1.0.9/libusb'
Making all in doc
make[2]: Entering directory `/share/libusb-1.0.9/doc'
make[2]: Nothing to be done for `all'.
make[2]: Leaving directory `/share/libusb-1.0.9/doc'
make[2]: Entering directory `/share/libusb-1.0.9'
make[2]: Nothing to be done for `all-am'.
make[2]: Leaving directory `/share/libusb-1.0.9'
make[1]: Leaving directory `/share/libusb-1.0.9'

/* make install的動作主要是編譯出libusb庫並加入到系統資料夾下 */
[[email protected] libusb-1.0.9]# make install
Making install in libusb
make[1]: Entering directory `/share/libusb-1.0.9/libusb'
make[2]: Entering directory `/share/libusb-1.0.9/libusb'
test -z "/usr/local/lib" || /bin/mkdir -p "/usr/local/lib"
 /bin/sh ../libtool   --mode=install /usr/bin/install -c   libusb-1.0.la '/usr/local/lib'
libtool: install: /usr/bin/install -c .libs/libusb-1.0.so.0.1.0 /usr/local/lib/libusb-1.0.so.0.1.0
libtool: install: (cd /usr/local/lib && { ln -s -f libusb-1.0.so.0.1.0 libusb-1.0.so.0 || { rm -f libusb-1.0.so.0 && ln -s libusb-1.0.so.0.1.0 libusb-1.0.so.0; }; })
libtool: install: (cd /usr/local/lib && { ln -s -f libusb-1.0.so.0.1.0 libusb-1.0.so || { rm -f libusb-1.0.so && ln -s libusb-1.0.so.0.1.0 libusb-1.0.so; }; })
libtool: install: /usr/bin/install -c .libs/libusb-1.0.lai /usr/local/lib/libusb-1.0.la
libtool: install: /usr/bin/install -c .libs/libusb-1.0.a /usr/local/lib/libusb-1.0.a
libtool: install: chmod 644 /usr/local/lib/libusb-1.0.a
libtool: install: ranlib /usr/local/lib/libusb-1.0.a
libtool: finish: PATH="/usr/lib/qt-3.3/bin:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/lib/ccache:/opt/EmbedSky/4.3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin:/sbin" ldconfig -n /usr/local/lib
----------------------------------------------------------------------
Libraries have been installed in:
   /usr/local/lib /* 這裡提示已經將庫加入到/usr/local/lib目錄，所以我們基於libusb程式設計的時候，需要包含這個庫 */

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:
   - add LIBDIR to the `LD_LIBRARY_PATH' environment variable
     during execution
   - add LIBDIR to the `LD_RUN_PATH' environment variable
     during linking
   - use the `-Wl,-rpath -Wl,LIBDIR' linker flag
   - have your system administrator add LIBDIR to `/etc/ld.so.conf'

See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.
----------------------------------------------------------------------
test -z "/usr/local/include/libusb-1.0" || /bin/mkdir -p "/usr/local/include/libusb-1.0"
 /usr/bin/install -c -m 644 libusb.h '/usr/local/include/libusb-1.0'
make[2]: Leaving directory `/share/libusb-1.0.9/libusb'
make[1]: Leaving directory `/share/libusb-1.0.9/libusb'
Making install in doc
make[1]: Entering directory `/share/libusb-1.0.9/doc'
make[2]: Entering directory `/share/libusb-1.0.9/doc'
make[2]: Nothing to be done for `install-exec-am'.
make[2]: Nothing to be done for `install-data-am'.
make[2]: Leaving directory `/share/libusb-1.0.9/doc'
make[1]: Leaving directory `/share/libusb-1.0.9/doc'
make[1]: Entering directory `/share/libusb-1.0.9'
make[2]: Entering directory `/share/libusb-1.0.9'
make[2]: Nothing to be done for `install-exec-am'.
test -z "/usr/local/lib/pkgconfig" || /bin/mkdir -p "/usr/local/lib/pkgconfig"
 /usr/bin/install -c -m 644 libusb-1.0.pc '/usr/local/lib/pkgconfig'
make[2]: Leaving directory `/share/libusb-1.0.9'
make[1]: Leaving directory `/share/libusb-1.0.9'

5.原始碼目錄下有example目錄，是libusb提供的測試程式listdev.c (列出usb裝置)

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1. #include <stdio.h>  
2. #include <sys/types.h>  
3. #include <libusb.h>  
4. staticvoid print_devs(libusb_device **devs)  
5. {  
6.     libusb_device *dev;  
7.     int i = 0;  
8.     while ((dev = devs[i++]) != NULL) {  
9.         struct libusb_device_descriptor desc;  
10.         int r = libusb_get_device_descriptor(dev, &desc);  
11.         if (r < 0) {  
12.             fprintf(stderr, "failed to get device descriptor");  
13.             return;  
14.         }  
15.         printf("%04x:%04x (bus %d, device %d)\n",  
16.             desc.idVendor, desc.idProduct,  
17.             libusb_get_bus_number(dev), libusb_get_device_address(dev));  
18.     }  
19. }  
20. int main(void)  
21. {  
22.     libusb_device **devs;  
23.     int r;  
24.     ssize_t cnt;  
25.     r = libusb_init(NULL);  
26.     if (r < 0)  
27.         return r;  
28.     cnt = libusb_get_device_list(NULL, &devs);  
29.     if (cnt < 0)  
30.         return (int) cnt;  
31.     print_devs(devs);  
32.     libusb_free_device_list(devs, 1);  
33.     libusb_exit(NULL);  
34.     return0;  
35. }  

編譯的時候我們可以用自帶的makefile生成可執行檔案，也可以用如下操作進行：(參考[2])

[[email protected] examples]# gcc -I/usr/local/include/libusb-1.0 listdevs.c -L/usr/local/lib -lusb-1.0

-I包含標頭檔案 ;-L連結庫

6.listdev的執行結果如下：

[[email protected] examples]# gcc -I/usr/local/include/libusb-1.0 listdevs.c -L/usr/local/lib -lusb-1.0
[[email protected] examples]# ./a.out 
1d6b:0002 (bus 1, device 1)
1d6b:0001 (bus 2, device 1)
0e0f:0003 (bus 2, device 2)
0e0f:0002 (bus 2, device 3)
0cf3:1006 (bus 1, device 3)
[[email protected] examples]# lsusb  /* 與lsusb命令得出的是一致 */
Bus 001 Device 003: ID 0cf3:1006 Atheros Communications, Inc. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 003: ID 0e0f:0002  
Bus 002 Device 002: ID 0e0f:0003  
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hubReference：

7.若想開啟除錯開關，看出libusb內部的執行情況

在libusb/libusbi.h中有如下程式碼

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1. #ifdef ENABLE_DEBUG_LOGGING  
2. #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)  
3. #else
4. #define usbi_dbg(...) do {} while(0)  
5. #endif  

所以說在makefile加上-DENABLE_DEBUG_LOGGING=1這個編譯選項即可.

在libusb的目錄下找到makefile(configure之後才會生成)，找到CFLAGS = -g -O2，替換為CFLAGS = -g -O2 -DENABLE_DEBUG_LOGGING=1

再次make和make install，切換到之前的listdev程式，可以看見已經打出libusb內部的呼叫順序：

[[email protected] examples]# ./listdevs 
libusb: 0.000000 debug [libusb_init] libusb-1.0.9
libusb: 0.003326 debug [find_usbfs_path] found usbfs at /dev/bus/usb
libusb: 0.004064 debug [op_init] found usb devices in sysfs
libusb: 0.004939 debug [usbi_add_pollfd] add fd 3 events 1
libusb: 0.005519 debug [usbi_io_init] using timerfd for timeouts
libusb: 0.006147 debug [usbi_add_pollfd] add fd 5 events 1
libusb: 0.006710 debug [libusb_init] created default context
libusb: 0.007273 debug [libusb_get_device_list] 
libusb: 0.011264 debug [sysfs_scan_device] scan usb1
libusb: 0.012133 debug [sysfs_scan_device] bus=1 dev=1
libusb: 0.012681 debug [enumerate_device] busnum 1 devaddr 1 session_id 257
libusb: 0.013244 debug [enumerate_device] allocating new device for 1/1 (session 257)
libusb: 0.013956 debug [sysfs_scan_device] scan usb2
libusb: 0.014740 debug [sysfs_scan_device] bus=2 dev=1
libusb: 0.015685 debug [enumerate_device] busnum 2 devaddr 1 session_id 513
libusb: 0.016251 debug [enumerate_device] allocating new device for 2/1 (session 513)
libusb: 0.016984 debug [sysfs_scan_device] scan 2-1
libusb: 0.017761 debug [sysfs_scan_device] bus=2 dev=2
libusb: 0.018467 debug [enumerate_device] busnum 2 devaddr 2 session_id 514
libusb: 0.018988 debug [enumerate_device] allocating new device for 2/2 (session 514)
libusb: 0.019789 debug [sysfs_scan_device] scan 2-2
libusb: 0.020473 debug [sysfs_scan_device] bus=2 dev=3
libusb: 0.021145 debug [enumerate_device] busnum 2 devaddr 3 session_id 515
libusb: 0.021742 debug [enumerate_device] allocating new device for 2/3 (session 515)
libusb: 0.022440 debug [sysfs_scan_device] scan 1-1
libusb: 0.023203 debug [sysfs_scan_device] bus=1 dev=3
libusb: 0.023986 debug [enumerate_device] busnum 1 devaddr 3 session_id 259
libusb: 0.024548 debug [enumerate_device] allocating new device for 1/3 (session 259)
libusb: 0.025266 debug [libusb_get_device_descriptor] 
1d6b:0002 (bus 1, device 1)
libusb: 0.026017 debug [libusb_get_device_descriptor] 
1d6b:0001 (bus 2, device 1)
libusb: 0.026479 debug [libusb_get_device_descriptor] 
0e0f:0003 (bus 2, device 2)
libusb: 0.026516 debug [libusb_get_device_descriptor] 
0e0f:0002 (bus 2, device 3)
libusb: 0.026576 debug [libusb_get_device_descriptor] 
0cf3:1006 (bus 1, device 3)
libusb: 0.026616 debug [libusb_unref_device] destroy device 1.1
libusb: 0.026636 debug [libusb_unref_device] destroy device 2.1
libusb: 0.026652 debug [libusb_unref_device] destroy device 2.2
libusb: 0.026667 debug [libusb_unref_device] destroy device 2.3
libusb: 0.026682 debug [libusb_unref_device] destroy device 1.3
libusb: 0.026698 debug [libusb_exit] 
libusb: 0.026731 debug [libusb_exit] destroying default context
libusb: 0.026747 debug [usbi_remove_pollfd] remove fd 3
libusb: 0.026778 debug [usbi_remove_pollfd] remove fd 5

PS:這裡還有一個問題：

[[email protected] test]# ./a.out 
./a.out: error while loading shared libraries: libusb-1.0.so.0: cannot open shared object file: No such file or directory
[[email protected] test]# /* 執行的時候若出現這個錯誤,只要先執行下面一句話即可 */
[[email protected] test]# export LD_LIBRARY_PATH=/usr/local/lib