📄 namei.c
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<!doctype html public "-//W3C//DTD HTML 3.2//EN"><html><head><title>Linux/fs/namei.c</title><meta http-equiv=Content-Type content="text/html; charset=gb2312"><base href="http://oldlinux.org/lxr/http/"></head><body bgcolor=white><div align=center> [<b><i>源代码浏览</i></b>] [<a href="diff/fs/namei.c">区别标定</a>] [<a href="ident">标识符搜索</a>] [<a href="search">文本搜索</a>] [<a href="find">文件搜索</a>]</div><h1 align=center> <a href="http:/"> OldLinux</a> <a href="http:blurb.html"> 交叉引用</a><br> <a href="source/">Linux</a>/<a href="source/fs/">fs</a>/<a href="source/fs/namei.c">namei.c</a></h1><div align=center> <b>版本:</b> [<a href="source/fs/namei.c?v=1.0">1.0</a>] [<a href="source/fs/namei.c?v=0.99.11">0.99.11</a>] [<a href="source/fs/namei.c?v=0.99">0.99</a>] [<a href="source/fs/namei.c?v=0.97">0.97</a>] [<a href="source/fs/namei.c?v=0.96a">0.96a</a>] [<a href="source/fs/namei.c?v=0.95">0.95</a>] [<a href="source/fs/namei.c?v=0.12">0.12</a>] [<b><i>0.11</i></b>] [<a href="source/fs/namei.c?v=0.01">0.01</a>] <br> <b>体系结构:</b> [<b><i>i386</i></b>] <br></div><hr><pre> <a name=L1 href="source/fs/namei.c#L1">1</a> <b><i>/*</i></b> <a name=L2 href="source/fs/namei.c#L2">2</a> <b><i> * linux/fs/namei.c</i></b> <a name=L3 href="source/fs/namei.c#L3">3</a> <b><i> *</i></b> <a name=L4 href="source/fs/namei.c#L4">4</a> <b><i> * (C) 1991 Linus Torvalds</i></b> <a name=L5 href="source/fs/namei.c#L5">5</a> <b><i> */</i></b> <a name=L6 href="source/fs/namei.c#L6">6</a> <a name=L7 href="source/fs/namei.c#L7">7</a> <b><i>/*</i></b> <a name=L8 href="source/fs/namei.c#L8">8</a> <b><i> * Some corrections by tytso.</i></b> <a name=L9 href="source/fs/namei.c#L9">9</a> <b><i> */</i></b> <a name=L10 href="source/fs/namei.c#L10">10</a> <a name=L11 href="source/fs/namei.c#L11">11</a> #include <linux/sched.h> <a name=L12 href="source/fs/namei.c#L12">12</a> #include <linux/kernel.h> <a name=L13 href="source/fs/namei.c#L13">13</a> #include <asm/segment.h> <a name=L14 href="source/fs/namei.c#L14">14</a> <a name=L15 href="source/fs/namei.c#L15">15</a> #include <string.h> <a name=L16 href="source/fs/namei.c#L16">16</a> #include <fcntl.h> <a name=L17 href="source/fs/namei.c#L17">17</a> #include <errno.h> <a name=L18 href="source/fs/namei.c#L18">18</a> #include <const.h> <a name=L19 href="source/fs/namei.c#L19">19</a> #include <sys/stat.h> <a name=L20 href="source/fs/namei.c#L20">20</a> <a name=L21 href="source/fs/namei.c#L21">21</a> #define <a href="ident?i=ACC_MODE">ACC_MODE</a>(<a href="ident?i=x">x</a>) (<i>"\004\002\006\377"</i>[(<a href="ident?i=x">x</a>)&<a href="ident?i=O_ACCMODE">O_ACCMODE</a>]) <a name=L22 href="source/fs/namei.c#L22">22</a> <a name=L23 href="source/fs/namei.c#L23">23</a> <b><i>/*</i></b> <a name=L24 href="source/fs/namei.c#L24">24</a> <b><i> * comment out this line if you want names > NAME_LEN chars to be</i></b> <a name=L25 href="source/fs/namei.c#L25">25</a> <b><i> * truncated. Else they will be disallowed.</i></b> <a name=L26 href="source/fs/namei.c#L26">26</a> <b><i> */</i></b> <a name=L27 href="source/fs/namei.c#L27">27</a> <b><i>/* #define NO_TRUNCATE */</i></b> <a name=L28 href="source/fs/namei.c#L28">28</a> <a name=L29 href="source/fs/namei.c#L29">29</a> #define <a href="ident?i=MAY_EXEC">MAY_EXEC</a> 1 <a name=L30 href="source/fs/namei.c#L30">30</a> #define <a href="ident?i=MAY_WRITE">MAY_WRITE</a> 2 <a name=L31 href="source/fs/namei.c#L31">31</a> #define <a href="ident?i=MAY_READ">MAY_READ</a> 4 <a name=L32 href="source/fs/namei.c#L32">32</a> <a name=L33 href="source/fs/namei.c#L33">33</a> <b><i>/*</i></b> <a name=L34 href="source/fs/namei.c#L34">34</a> <b><i> * permission()</i></b> <a name=L35 href="source/fs/namei.c#L35">35</a> <b><i> *</i></b> <a name=L36 href="source/fs/namei.c#L36">36</a> <b><i> * is used to check for read/write/execute permissions on a file.</i></b> <a name=L37 href="source/fs/namei.c#L37">37</a> <b><i> * I don't know if we should look at just the euid or both euid and</i></b> <a name=L38 href="source/fs/namei.c#L38">38</a> <b><i> * uid, but that should be easily changed.</i></b> <a name=L39 href="source/fs/namei.c#L39">39</a> <b><i> */</i></b> <a name=L40 href="source/fs/namei.c#L40">40</a> static int <a href="ident?i=permission">permission</a>(struct <a href="ident?i=m_inode">m_inode</a> * inode,int mask) <a name=L41 href="source/fs/namei.c#L41">41</a> { <a name=L42 href="source/fs/namei.c#L42">42</a> int mode = inode->i_mode; <a name=L43 href="source/fs/namei.c#L43">43</a> <a name=L44 href="source/fs/namei.c#L44">44</a> <b><i>/* special case: not even root can read/write a deleted file */</i></b> <a name=L45 href="source/fs/namei.c#L45">45</a> if (inode->i_dev && !inode->i_nlinks) <a name=L46 href="source/fs/namei.c#L46">46</a> return 0; <a name=L47 href="source/fs/namei.c#L47">47</a> else if (<a href="ident?i=current">current</a>->euid==inode->i_uid) <a name=L48 href="source/fs/namei.c#L48">48</a> mode >>= 6; <a name=L49 href="source/fs/namei.c#L49">49</a> else if (<a href="ident?i=current">current</a>->egid==inode->i_gid) <a name=L50 href="source/fs/namei.c#L50">50</a> mode >>= 3; <a name=L51 href="source/fs/namei.c#L51">51</a> if (((mode & mask & 0007) == mask) || <a href="ident?i=suser">suser</a>()) <a name=L52 href="source/fs/namei.c#L52">52</a> return 1; <a name=L53 href="source/fs/namei.c#L53">53</a> return 0; <a name=L54 href="source/fs/namei.c#L54">54</a> } <a name=L55 href="source/fs/namei.c#L55">55</a> <a name=L56 href="source/fs/namei.c#L56">56</a> <b><i>/*</i></b> <a name=L57 href="source/fs/namei.c#L57">57</a> <b><i> * ok, we cannot use strncmp, as the name is not in our data space.</i></b> <a name=L58 href="source/fs/namei.c#L58">58</a> <b><i> * Thus we'll have to use match. No big problem. Match also makes</i></b> <a name=L59 href="source/fs/namei.c#L59">59</a> <b><i> * some sanity tests.</i></b> <a name=L60 href="source/fs/namei.c#L60">60</a> <b><i> *</i></b> <a name=L61 href="source/fs/namei.c#L61">61</a> <b><i> * NOTE! unlike strncmp, match returns 1 for success, 0 for failure.</i></b> <a name=L62 href="source/fs/namei.c#L62">62</a> <b><i> */</i></b> <a name=L63 href="source/fs/namei.c#L63">63</a> static int <a href="ident?i=match">match</a>(int len,const char * name,struct <a href="ident?i=dir_entry">dir_entry</a> * de) <a name=L64 href="source/fs/namei.c#L64">64</a> { <a name=L65 href="source/fs/namei.c#L65">65</a> register int same __asm__(<i>"ax"</i>); <a name=L66 href="source/fs/namei.c#L66">66</a> <a name=L67 href="source/fs/namei.c#L67">67</a> if (!de || !de->inode || len > <a href="ident?i=NAME_LEN">NAME_LEN</a>) <a name=L68 href="source/fs/namei.c#L68">68</a> return 0; <a name=L69 href="source/fs/namei.c#L69">69</a> if (len < <a href="ident?i=NAME_LEN">NAME_LEN</a> && de->name[len]) <a name=L70 href="source/fs/namei.c#L70">70</a> return 0; <a name=L71 href="source/fs/namei.c#L71">71</a> __asm__(<i>"cld\n\t"</i> <a name=L72 href="source/fs/namei.c#L72">72</a> <i>"fs ; repe ; cmpsb\n\t"</i> <a name=L73 href="source/fs/namei.c#L73">73</a> <i>"setz %%al"</i> <a name=L74 href="source/fs/namei.c#L74">74</a> :<i>"=a"</i> (same) <a name=L75 href="source/fs/namei.c#L75">75</a> :<i>""</i> (0),<i>"S"</i> ((long) name),<i>"D"</i> ((long) de->name),<i>"c"</i> (len) <a name=L76 href="source/fs/namei.c#L76">76</a> :<i>"cx"</i>,<i>"di"</i>,<i>"si"</i>); <a name=L77 href="source/fs/namei.c#L77">77</a> return same; <a name=L78 href="source/fs/namei.c#L78">78</a> } <a name=L79 href="source/fs/namei.c#L79">79</a> <a name=L80 href="source/fs/namei.c#L80">80</a> <b><i>/*</i></b> <a name=L81 href="source/fs/namei.c#L81">81</a> <b><i> * find_entry()</i></b> <a name=L82 href="source/fs/namei.c#L82">82</a> <b><i> *</i></b> <a name=L83 href="source/fs/namei.c#L83">83</a> <b><i> * finds an entry in the specified directory with the wanted name. It</i></b> <a name=L84 href="source/fs/namei.c#L84">84</a> <b><i> * returns the cache buffer in which the entry was found, and the entry</i></b> <a name=L85 href="source/fs/namei.c#L85">85</a> <b><i> * itself (as a parameter - res_dir). It does NOT read the inode of the</i></b> <a name=L86 href="source/fs/namei.c#L86">86</a> <b><i> * entry - you'll have to do that yourself if you want to.</i></b> <a name=L87 href="source/fs/namei.c#L87">87</a> <b><i> *</i></b> <a name=L88 href="source/fs/namei.c#L88">88</a> <b><i> * This also takes care of the few special cases due to '..'-traversal</i></b> <a name=L89 href="source/fs/namei.c#L89">89</a> <b><i> * over a pseudo-root and a mount point.</i></b> <a name=L90 href="source/fs/namei.c#L90">90</a> <b><i> */</i></b> <a name=L91 href="source/fs/namei.c#L91">91</a> static struct <a href="ident?i=buffer_head">buffer_head</a> * <a href="ident?i=find_entry">find_entry</a>(struct <a href="ident?i=m_inode">m_inode</a> ** dir, <a name=L92 href="source/fs/namei.c#L92">92</a> const char * name, int namelen, struct <a href="ident?i=dir_entry">dir_entry</a> ** res_dir) <a name=L93 href="source/fs/namei.c#L93">93</a> { <a name=L94 href="source/fs/namei.c#L94">94</a> int entries; <a name=L95 href="source/fs/namei.c#L95">95</a> int block,i; <a name=L96 href="source/fs/namei.c#L96">96</a> struct <a href="ident?i=buffer_head">buffer_head</a> * bh; <a name=L97 href="source/fs/namei.c#L97">97</a> struct <a href="ident?i=dir_entry">dir_entry</a> * de; <a name=L98 href="source/fs/namei.c#L98">98</a> struct <a href="ident?i=super_block">super_block</a> * sb; <a name=L99 href="source/fs/namei.c#L99">99</a> <a name=L100 href="source/fs/namei.c#L100">100</a> #ifdef NO_TRUNCATE<a name=L101 href="source/fs/namei.c#L101">101</a> if (namelen > <a href="ident?i=NAME_LEN">NAME_LEN</a>)<a name=L102 href="source/fs/namei.c#L102">102</a> return <a href="ident?i=NULL">NULL</a>;<a name=L103 href="source/fs/namei.c#L103">103</a> #else<a name=L104 href="source/fs/namei.c#L104">104</a> if (namelen > <a href="ident?i=NAME_LEN">NAME_LEN</a>)<a name=L105 href="source/fs/namei.c#L105">105</a> namelen = <a href="ident?i=NAME_LEN">NAME_LEN</a>;⌨️ 快捷键说明
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