From 58a58e234fb5f1e0e51dff0db3ee86b49e90eddc Mon Sep 17 00:00:00 2001 From: Bruce Leidl Date: Wed, 2 Jan 2019 13:28:51 -0500 Subject: [PATCH] Search for images in a directory by metainfo rather than filename. --- libcitadel/src/resource.rs | 177 +++++++++++++++++++++++++++++++------ 1 file changed, 149 insertions(+), 28 deletions(-) diff --git a/libcitadel/src/resource.rs b/libcitadel/src/resource.rs index f24877d..66dd921 100644 --- a/libcitadel/src/resource.rs +++ b/libcitadel/src/resource.rs @@ -1,4 +1,5 @@ -use std::fs::{self, File}; +use std::fs::{self,File,DirEntry}; +use std::ffi::OsStr; use std::io::{self,Seek,SeekFrom}; use std::path::{Path, PathBuf}; @@ -33,40 +34,36 @@ pub struct ResourceImage { } impl ResourceImage { - /// Locate and return a resource image with `name`. + /// Locate and return a resource image of type `image_type`. /// First the /run/images directory is searched, and if not found there, /// the image will be searched for in /storage/resources/$channel - pub fn find(name: &str) -> Result { - let filename = ResourceImage::image_filename(name); - - let run_path = Path::new(RUN_DIRECTORY).join(&filename); - + pub fn find(image_type: &str) -> Result { let channel = ResourceImage::read_rootfs_channel()?; - let storage_path = Path::new(STORAGE_BASEDIR).join(channel).join(&filename); - if run_path.exists() { - return ResourceImage::from_path(run_path); + info!("Searching run directory for image {} with channel {}", image_type, channel); + + if let Some(image) = search_directory(RUN_DIRECTORY, image_type, Some(&channel))? { + return Ok(image); } if !ResourceImage::ensure_storage_mounted()? { bail!("Unable to mount /storage"); } - if storage_path.exists() { - ResourceImage::from_path(storage_path) - } else { - Err(format_err!("Failed to find resource image: {}", name)) + let storage_path = Path::new(STORAGE_BASEDIR).join(&channel); + + if let Some(image) = search_directory(storage_path, image_type, Some(&channel))? { + return Ok(image); } + + Err(format_err!("Failed to find resource image of type: {}", image_type)) } /// Locate a rootfs image in /run/images and return it pub fn find_rootfs() -> Result { - let rootfs_path = Path::new(RUN_DIRECTORY).join(ResourceImage::image_filename("rootfs")); - if rootfs_path.exists() { - info!("Found rootfs image at {}", rootfs_path.display()); - ResourceImage::from_path(rootfs_path) - } else { - Err(format_err!("Failed to find rootfs resource image")) + match search_directory(RUN_DIRECTORY, "rootfs", None)? { + Some(image) => Ok(image), + None => Err(format_err!("Failed to find rootfs resource image")), } } @@ -332,22 +329,146 @@ impl ResourceImage { } fn read_rootfs_channel() -> Result { - let s = fs::read_to_string("/sysroot/etc/citadel-channel") - .context("Failed to open /sysroot/etc/citadel-channel")?; + let channel_file = if Path::new("/etc/initrd-release").exists() { + "/sysroot/etc/citadel-channel" + } else { + "/etc/citadel-channel" + }; + + let s = fs::read_to_string(channel_file) + .context(format!("Failed to open {}", channel_file))?; + match s.split_whitespace().next() { Some(s) => Ok(s.to_owned()), None => Err(format_err!("Failed to parse /sysroot/etc/citadel-channel contents")), } } +} - fn image_filename(image_type: &str) -> String { - if image_type == "modules" { - let utsname = util::uname(); - let v = utsname.release().split("-").collect::>(); - format!("citadel-modules-{}.img", v[0]) +// Search directory for a resource image with the specified channel and image_type +// in the image header metainfo. If multiple matches are found, return the image +// with the highest version number. If multiple images have the same highest version +// number, return the image with the newest file creation time. +fn search_directory>(dir: P, image_type: &str, channel: Option<&str>) -> Result> { + if !dir.as_ref().exists() { + return Ok(None) + } + + let mut best = None; + + let mut matches = all_matching_images(dir.as_ref(), image_type, channel)?; + info!("Found {} matching images", matches.len()); + + if channel.is_none() { + if matches.is_empty() { + return Ok(None); + } + if matches.len() > 1 { + warn!("Found multiple images of type {} in {}, but no channel specified. Returning arbitrary image", + image_type, dir.as_ref().display()); + } + return Ok(Some(matches.remove(0))) + } + + for image in matches { + best = Some(compare_images(best, image)?); + } + + Ok(best) +} + +// Compare two images (a and b) and return the image with the highest version number. If +// both images have the same version return the one with the newest file creation +// time. Image a is an Option type, if it is None then just return b. +fn compare_images(a: Option, b: ResourceImage) -> Result { + let a = match a { + Some(img) => img, + None => return Ok(b), + }; + + let ver_a = a.metainfo().version(); + let ver_b = b.metainfo().version(); + + if ver_a > ver_b { + Ok(a) + } else if ver_b > ver_a { + Ok(b) + } else { + // versions are the same so compare file times + let a_time = a.path().metadata()?.created()?; + let b_time = b.path().metadata()?.created()?; + if a_time > b_time { + Ok(a) } else { - format!("citadel-{}.img", image_type) + Ok(b) } } } + +fn current_kernel_version() -> String { + let utsname = util::uname(); + let v = utsname.release().split("-").collect::>(); + v[0].to_string() +} + +// +// Read a directory search for ResourceImages which match the channel +// and image_type. +// +fn all_matching_images(dir: &Path, image_type: &str, channel: Option<&str>) -> Result> { + let kernel_version = current_kernel_version(); + let kv = if image_type == "modules" { + Some(kernel_version.as_str()) + } else { + None + }; + + let mut v = Vec::new(); + for entry in fs::read_dir(dir)? { + maybe_add_dir_entry(entry?, image_type, channel, kv, &mut v)?; + } + Ok(v) +} + +// Examine a directory entry to determine if it is a resource image which +// matches a given channel and image_type. If the image_type is "modules" +// then also match the kernel-version field. If channel is None then don't +// consider the channel in the match. +// +// If the entry is a match, then instantiate a ResourceImage and add it to +// the images vector. +fn maybe_add_dir_entry(entry: DirEntry, + image_type: &str, + channel: Option<&str>, + kernel_version: Option<&str>, + images: &mut Vec) -> Result<()> { + + let path = entry.path(); + if Some(OsStr::new("img")) != path.extension() { + return Ok(()) + } + let meta = entry.metadata()?; + if meta.len() < ImageHeader::HEADER_SIZE as u64 { + return Ok(()) + } + let header = ImageHeader::from_file(&path)?; + if !header.is_magic_valid() { + return Ok(()) + } + + let metainfo = header.metainfo()?; + + info!("Found an image type={} channel={} kernel={:?}", metainfo.image_type(), metainfo.channel(), metainfo.kernel_version()); + + if let Some(channel) = channel { + if metainfo.channel() != channel { + return Ok(()); + } + } + + if metainfo.image_type() == image_type && metainfo.kernel_version() == kernel_version { + images.push(ResourceImage::new(&path, header, metainfo)); + } + Ok(()) +}