Changeset 23309 in vbox for trunk

Timestamp:

Sep 24, 2009 7:44:27 PM (15 years ago)

Author:

vboxsync

Message:

iprt/linux: add APIs for locating device nodes to sysfs APIs

Location:

trunk

Files:

• include/iprt/linux/sysfs.h (modified) (3 diffs)
• src/VBox/Runtime/r3/linux/sysfs.cpp (modified) (5 diffs)

trunk/include/iprt/linux/sysfs.h

@@ -36 +36 @@
 #include <iprt/stdarg.h>
 
+#include <sys/types.h>
 
 RT_C_DECLS_BEGIN
@@ -119 +120 @@
 
 /**
+ * Reads a device number from a sysfs file.
+ *
+ * @returns device number on success, 0 and errno on failure.
+ * @param   pszFormat   The filename format, either absolute or relative to "/sys/".
+ * @param   va          Format args.
+ */
+RTDECL(dev_t) RTLinuxSysFsReadDevNumFileV(const char *pszFormat, va_list va);
+
+/**
+ * Reads a device number from a sysfs file.
+ *
+ * @returns device number on success, 0 and errno on failure.
+ * @param   pszFormat   The filename format, either absolute or relative to "/sys/".
+ * @param   ...         Format args.
+ */
+RTDECL(dev_t) RTLinuxSysFsReadDevNumFile(const char *pszFormat, ...);
+
+/**
  * Reads a string from a sysfs file.  If the file contains a newline, we only
  * return the text up until there.
@@ -178 +197 @@
 RTDECL(ssize_t) RTLinuxSysFsGetLinkDest(char *pszBuf, size_t cchBuf, const char *pszFormat, ...);
 
+/**
+ * Find the path of a device node under /dev, given then device number.  This
+ * function will recursively search under /dev until it finds a device node
+ * matching @a devnum, and store the path into @a pszBuf.  The caller may
+ * provide an expected path in pszSuggestion, which will be tried before
+ * searching, but due to the variance in Linux systems it can be hard to always
+ * correctly predict the path.
+ * 
+ * @returns the number of characters written on success, -1 and errno on
+ *          failure
+ * @returns -1 and ENOENT if no matching device node could be found
+ * @param  devNum         the device number to search for
+ * @param  fMode          the type of device - only RTFS_TYPE_DEV_CHAR
+ *                        and RTFS_TYPE_DEV_BLOCK are valid values
+ * @param  pszBuf         where to store the path
+ * @param  cchBuf         the size of the buffer
+ * @param  pszSuggestion  the expected path format of the device node, either
+ *                        absolute or relative to "/dev" (optional)
+ * @param  va             Format args.
+ */
+RTDECL(ssize_t) RTLinuxFindDevicePathV(dev_t devNum, RTFMODE fMode, char *pszBuf, size_t cchBuf, const char *pszSuggestion, va_list va);
+
+/**
+ * Find the path of a device node under /dev, given then device number.  This
+ * function will recursively search under /dev until it finds a device node
+ * matching @a devnum, and store the path into @a pszBuf.  The caller may
+ * provide an expected path in pszSuggestion, which will be tried before
+ * searching, but due to the variance in Linux systems it can be hard to always
+ * correctly predict the path.
+ * 
+ * @returns the number of characters written on success, -1 and errno on
+ *          failure
+ * @returns -1 and ENOENT if no matching device node could be found
+ * @param  devNum         the device number to search for
+ * @param  fMode          the type of device - only RTFS_TYPE_DEV_CHAR
+ *                        and RTFS_TYPE_DEV_BLOCK are valid values
+ * @param  pszBuf         where to store the path
+ * @param  cchBuf         the size of the buffer
+ * @param  pszSuggestion  the expected path format of the device node, either
+ *                        absolute or relative to "/dev" (optional)
+ * @param  ...            Format args.
+ */
+RTDECL(ssize_t) RTLinuxFindDevicePath(dev_t devNum, RTFMODE fMode, char *pszBuf, size_t cchBuf, const char *pszSuggestion, ...);
+
 /** @} */
 

trunk/src/VBox/Runtime/r3/linux/sysfs.cpp

@@ -36 +36 @@
 #include <iprt/linux/sysfs.h>
 #include <iprt/assert.h>
+#include <iprt/dir.h>
+#include <iprt/err.h>
+#include <iprt/fs.h>
 #include <iprt/param.h>
 #include <iprt/path.h>
@@ -46 +49 @@
 #include <sys/fcntl.h>
 #include <errno.h>
+
+
+/**
+ * Constructs the path of a sysfs file from the format paramaters passed,
+ * prepending a prefix if the path is relative.
+ *
+ * @returns The number of characters returned, or -1 and errno set to ERANGE on
+ *        failure.
+ *
+ * @param   pszPrefix  The prefix to prepend if the path is relative.  Must end
+ *                     in '/'.
+ * @param   pszBuf     Where to write the path.  Must be at least
+ *                     sizeof(@a pszPrefix) characters long
+ * @param   cchBuf     The size of the buffer pointed to by @a pszBuf.
+ * @param   pszFormat  The name format, either absolute or relative to "/sys/".
+ * @param   va         The format args.
+ */
+static ssize_t rtLinuxConstructPathV(char *pszBuf, size_t cchBuf,
+                                     const char *pszPrefix,
+                                     const char *pszFormat, va_list va)
+{
+    size_t cchPrefix = strlen(pszPrefix);
+    AssertReturnStmt(pszPrefix[cchPrefix - 1] == '/', errno = ERANGE, -1);
+    AssertReturnStmt(cchBuf > cchPrefix + 1, errno = ERANGE, -1);
+
+    size_t cch = RTStrPrintfV(pszBuf, cchBuf, pszFormat, va);
+    if (*pszBuf != '/')
+    {
+        AssertReturnStmt(cchBuf >= cch + cchPrefix + 1, errno = ERANGE, -1);
+        memmove(pszBuf + cchPrefix, pszBuf, cch + 1);
+        memcpy(pszBuf, pszPrefix, cchPrefix);
+        cch += cchPrefix;
+    }
+    return cch;
+}
+
+
+/**
+ * Constructs the path of a sysfs file from the format paramaters passed,
+ * prepending a prefix if the path is relative.
+ *
+ * @returns The number of characters returned, or -1 and errno set to ERANGE on
+ *        failure.
+ *
+ * @param   pszPrefix  The prefix to prepend if the path is relative.  Must end
+ *                     in '/'.
+ * @param   pszBuf     Where to write the path.  Must be at least
+ *                     sizeof(@a pszPrefix) characters long
+ * @param   cchBuf     The size of the buffer pointed to by @a pszBuf.
+ * @param   pszFormat  The name format, either absolute or relative to "/sys/".
+ * @param   ...        The format args.
+ */
+static ssize_t rtLinuxConstructPath(char *pszBuf, size_t cchBuf,
+                                    const char *pszPrefix,
+                                    const char *pszFormat, ...)
+{
+    va_list va;
+    va_start(va, pszFormat);
+    int rc = rtLinuxConstructPathV(pszBuf, cchBuf, pszPrefix, pszFormat, va);
+    va_end(va);
+    return rc;
+}
 
 
@@ -63 +128 @@
 static ssize_t rtLinuxSysFsConstructPath(char *pszBuf, size_t cchBuf, const char *pszFormat, va_list va)
 {
-    static const char s_szPrefix[] = "/sys/";
-    AssertReturnStmt(cchBuf > sizeof(s_szPrefix), errno = ERANGE, -1);
-
-    size_t cch = RTStrPrintfV(pszBuf, cchBuf, pszFormat, va);
-    if (*pszBuf != '/')
-    {
-        AssertReturnStmt(cchBuf >= cch + sizeof(s_szPrefix), errno = ERANGE, -1);
-        memmove(pszBuf + sizeof(s_szPrefix) - 1, pszBuf, cch + 1);
-        memcpy(pszBuf, s_szPrefix, sizeof(s_szPrefix) - 1);
-        cch += sizeof(s_szPrefix) - 1;
-    }
-    return cch;
+    return rtLinuxConstructPathV(pszBuf, cchBuf, "/sys/", pszFormat, va);
 }
 
@@ -185 +239 @@
 
 
+RTDECL(dev_t) RTLinuxSysFsReadDevNumFileV(const char *pszFormat, va_list va)
+{
+    int fd = RTLinuxSysFsOpenV(pszFormat, va);
+    if (fd == -1)
+        return 0;
+
+    dev_t devNum = 0;
+    char szNum[128];
+    ssize_t cchNum = RTLinuxSysFsReadStr(fd, szNum, sizeof(szNum));
+    if (cchNum > 0)
+    {
+        uint32_t u32Maj = 0;
+        uint32_t u32Min = 0;
+        char *pszNext = NULL;
+        int rc = RTStrToUInt32Ex(szNum, &pszNext, 10, &u32Maj);
+        if (RT_FAILURE(rc) || (rc != VWRN_TRAILING_CHARS) || (*pszNext != ':'))
+            errno = EINVAL;
+        else
+        {
+            rc = RTStrToUInt32Ex(pszNext + 1, NULL, 10, &u32Min);
+            if (   rc != VINF_SUCCESS
+                && rc != VWRN_TRAILING_CHARS
+                && rc != VWRN_TRAILING_SPACES)
+                errno = EINVAL;
+            else
+            {
+                errno = 0;
+                devNum = makedev(u32Maj, u32Min);
+            }
+        }
+    }
+    else if (cchNum == 0)
+        errno = EINVAL;
+
+    RTLinuxSysFsClose(fd);
+    return devNum;
+}
+
+
+RTDECL(dev_t) RTLinuxSysFsReadDevNumFile(const char *pszFormat, ...)
+{
+    va_list va;
+    va_start(va, pszFormat);
+    dev_t devNum = RTLinuxSysFsReadDevNumFileV(pszFormat, va);
+    va_end(va);
+    return devNum;
+}
+
+
 RTDECL(ssize_t) RTLinuxSysFsReadStrFileV(char *pszBuf, size_t cchBuf, const char *pszFormat, va_list va)
 {
@@ -269 +372 @@
 }
 
+
+static ssize_t rtLinuxFindDevicePathRecursive(dev_t devNum, RTFMODE fMode,
+                                              const char *pszBasePath,
+                                              char *pszBuf, size_t cchBuf)
+{
+    PRTDIR pDir = NULL;
+    RTDIRENTRYEX entry = { {0} };
+    int vrc = VINF_SUCCESS;
+    ssize_t rc;
+
+    vrc = RTDirOpen(&pDir, pszBasePath);
+    if (RT_SUCCESS(vrc))
+        while (true)
+        {
+            vrc = RTDirReadEx(pDir, &entry, NULL, RTFSOBJATTRADD_UNIX);
+            if (RT_FAILURE(vrc))
+            {
+                errno =   (vrc == VERR_NO_MORE_FILES) ? ENOENT
+                        : (vrc == VERR_BUFFER_OVERFLOW) ? EOVERFLOW
+                        : EIO;
+                rc = -1;
+                break;
+            }
+            if (RTFS_IS_SYMLINK(entry.Info.Attr.fMode))
+                continue;
+            if (   (entry.Info.Attr.u.Unix.Device == devNum)
+                && (   (   (fMode == RTFS_TYPE_DEV_CHAR)
+                        && RTFS_IS_DEV_CHAR(entry.Info.Attr.fMode))
+                    || (   (fMode == RTFS_TYPE_DEV_BLOCK)
+                        && RTFS_IS_DEV_BLOCK(entry.Info.Attr.fMode))))
+            {
+                rc = rtLinuxConstructPath(pszBuf, cchBuf, pszBasePath, "%s",
+                                          entry.szName);
+                break;
+            }
+            if (!RTFS_IS_DIRECTORY(entry.Info.Attr.fMode))
+                continue;
+            if (entry.szName[0] == '.')
+                continue;
+            char szPath[RTPATH_MAX];
+            /** @todo this is a temporary hack, as RTDirReadEx currently
+             * doesn't know about symbolic links */
+            rc = rtLinuxConstructPath(szPath, sizeof(szPath), pszBasePath,
+                                      "%s", entry.szName);
+            if (rc < 0)
+                break;
+            struct stat Stat = { 0 };
+            if (   lstat(szPath, &Stat) < 0
+                || S_ISLNK(Stat.st_mode))
+                continue;
+            /* @todo ends here */
+            rc = rtLinuxConstructPath(szPath, sizeof(szPath), pszBasePath,
+                                      "%s/", entry.szName);
+            if (rc < 0)
+                break;
+            rc = rtLinuxFindDevicePathRecursive(devNum, fMode, szPath,
+                                                pszBuf, cchBuf);
+            if ((rc >= 0) || errno != ENOENT)
+                break;
+        }
+    else
+    {
+        rc = -1;
+        errno = RTErrConvertToErrno(vrc);
+    }
+    RTDirClose(pDir);
+    return rc;
+}
+
+
+RTDECL(ssize_t) RTLinuxFindDevicePathV(dev_t devNum, RTFMODE fMode,
+                                       char *pszBuf, size_t cchBuf,
+                                       const char *pszSuggestion, va_list va)
+{
+    AssertReturnStmt(cchBuf >= 2, errno = EINVAL, -1);
+    AssertReturnStmt(   (fMode == RTFS_TYPE_DEV_CHAR)
+                     || (fMode == RTFS_TYPE_DEV_BLOCK),
+                     errno = EINVAL, -1);
+
+    if (!pszSuggestion)
+        return rtLinuxFindDevicePathRecursive(devNum, fMode, "/dev/",
+                                              pszBuf, cchBuf);
+
+    /*
+     * Construct the filename and read the link.
+     */
+    char szFilename[RTPATH_MAX];
+    int rc = rtLinuxConstructPathV(szFilename, sizeof(szFilename), "/dev/",
+                                   pszSuggestion, va);
+    if (rc == -1)
+        return -1;
+
+    /*
+     * Check whether the caller's suggestion was right.
+     */
+    /** @todo Should we just be using POSIX stat here? */
+    RTFSOBJINFO info = {0};
+    int vrc = RTPathQueryInfo(szFilename, &info, RTFSOBJATTRADD_UNIX);
+    if (RT_FAILURE(vrc))
+    {
+        errno =   (vrc == VERR_PATH_NOT_FOUND) ? ENOENT
+                : (vrc == VERR_FILE_NOT_FOUND) ? ENOENT
+                : EIO;
+        return -1;
+    }
+    if (   (info.Attr.u.Unix.Device == devNum)
+        && (   (   (fMode == RTFS_TYPE_DEV_CHAR)
+                && RTFS_IS_DEV_CHAR(info.Attr.fMode))
+            || (   (fMode == RTFS_TYPE_DEV_BLOCK)
+                && RTFS_IS_DEV_BLOCK(info.Attr.fMode))))
+    {
+        size_t cchPath = strlen(szFilename) + 1;
+        if (cchPath > cchBuf)
+        {
+            errno = EOVERFLOW;
+            return -1;
+        }
+        strcpy(pszBuf, szFilename);
+        return cchPath;
+    }
+
+    /* If the suggestion was wrong, try the brute force method */
+    return rtLinuxFindDevicePathRecursive(devNum, fMode, "/dev/",
+                                          pszBuf, cchBuf);
+}
+
+
+RTDECL(ssize_t) RTLinuxFindDevicePath(dev_t devNum, RTFMODE fMode,
+                                      char *pszBuf, size_t cchBuf,
+                                      const char *pszSuggestion, ...)
+{
+    va_list va;
+    va_start(va, pszSuggestion);
+    int rc = RTLinuxFindDevicePathV(devNum, fMode, pszBuf, cchBuf,
+                                    pszSuggestion, va);
+    va_end(va);
+    return rc;
+}